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University  of  California  •  Berkeley 


GOTTLIEB      DAIMLER 

(1834-1899) 
INVENTOR    OF    THE    PRACTICAL    HIGH-SPEED   GASOLINE    MOTOR 

AND 

"FATHER  OF  THE  AUTOMOBILE" 


SECOND  REVISED  EDITION 

SELF-PROPELLED  VEHICLES 

A   PRACTICAL  TREATISE 


ON   THE 


THEORY,  CONSTRUCTION,  OPERATION,   CARE 
AND  MANAGEMENT 


OF  ALL  FORMS    OF 


AUTOMOBILES 

BY 

JAMES  E.  HOMANS,  A.  M. 


WITH  UPWARDS  OF  500  ILLUSTRATIONS  AND  DIAGRAMS,  GIVING  THE  ESSEN 

TIAL  DETAILS  OF  CONSTRUCTION  AND  MANY  IMPORTANT  POINTS  ON 

THE  SUCCESSFUL  OPERATION  OF  THE  VARIOUS  TYPES  OF  MOTOR 

CARRIAGES  DRIVEN  BY  STEAM,  GASOLINE  AND  ELECTRICITY. 


NEW  YORK,  U.  S.  A. 

THEO.    AUDEL  &   COMPANY 

SIXTY-THREE  FIFTH    AVENUE 

1904 


COPYRIGHTED  1902  AND   1904 

BY 

THEO.  AUDEL  &  COMPANY 


PREFACE. 

IN  presenting  this  second  edition  of  "  Self -Propelled  Vehicles" 
to  readers  interested  in  automobile  matters,  and  to  the 

public  in  general,  some  few  words  of  explanation  are  neces- 
sary. The  automobile,  considered  as  a  practical  machine,  occupies 
a  peculiar  place,  from  both  mechanical  and  popular  points  of  view. 
It  must  be  carefully  designed  and  thoroughly  equipped  to  serve 
its  purposes  under  all  the  trying  conditions  of  its  use.  It  must, 
furthermore,  be  of  simple  and  strong  construction,  so  as  to  render 
disablements  in  service  and  consequent  repairs — often  at  points 
distant  from  mechanics  skilled  in  the  special  field — as  few  and  as 
unimportant  as  possible.  L,ast,  but  most  conspicuous,  it  must 
be  readily  controlled  and  operated  in  the  large  majority  of  in- 
stances by  persons  who  do  not  consider  that  the  pleasures  derived 
from  * '  motoring  ' '  warrant  them  in  becoming  well-informed  in 
engineering  matters. 

If  the  owner  of  a  steam  carriage  burns  out  his  boiler  every 
time  he  takes  an  outing,  he  blames  the  builder  of  the  machine 
rather  than  his  own  ignorance  of  steam  engine  theory  and  prac- 
tice. If  the  owner  of  a  gasoline  carriage  meets  with  any  one  of 
the  several  common  accidents  that  result  from  simple  carelessness 
and  neglect,  he  forthwith  announces  that  the  automobile  is  not 
as  yet  a  practical  machine,  and  becomes  a  stalwart  champion  of 
the  trusty  horse,  whom  Nature  herself  repairs,  so  long  as  feed 
and  water  are  not  forgotten. 

For  the  practical  information  of  such  persons  as  have  neither 
the  time  nor  inclination  to  delve  deeper  into  the  subtleties  of 
mechanics  than  the  construction  and  management  of  their  own 
machine  requires,  this  book  has  been  planned. 

The  task  is  by  no  means  an  easy  one,  both  from  the  multi- 
plicity of  details  involved  and  from  the  constant  necessity  of 


iv  PREFACE. 

making  explanations  that  shall  be  perfectly  clear.  Furthermore, 
no  book  of  reasonable  compass  could  possibly  include  specific 
descriptions  and  directions  for  the  management  of  even  the 
majority  of  practical  motor  carriages  now  on  the  market.  Nor 
would  such  a  work  be  of  general  interest  to  the  reading  public. 
The  best  that  can  be  done,  therefore,  is  to  give  the  principles  of 
theory,  construction  and  operation  as  briefly  and  explicitly  as 
possible,  and  to  illustrate  them  by  the  constructions  used  on  such 
machines  as  have  proved  their  title  to  be  called  typical. 

It  is  hoped  that  the  treatment  given  will  make  the  book 
serviceable  to  owners  and  those  desiring  to  qualify  as  practical 
chauffeurs,  so  far  as  the  essential  knowledge  may  be  imparted  by 
a  book.  There  are,  of  course,  many  things  that  will  not  be  per- 
fectly clear  without  practical  experience,  also  such  divergencies 
of  construction  and  operative  method  as  will  prove  decidedly 
puzzling  to  the  novice.  However,  by  thoroughly  understanding 
the  principles  on  which  all  constructions  necessarily  rest  these 
may  rapidly  be  mastered. 


TABLE  OF  CONTENTS. 


CHAPTER. 

I. — THE  TYPES  AND  MERITS  OF  AUTOMOBILES 

II. — A    BRIEF    HISTORY   OF    SELF- PROPELLED 
VEHICLES 

III. — How  A  MOTOR  CARRIAGE  TURNS   . 

IV. — STEERING  A  MOTOR  CARRIAGE  .... 

V. — DEVICES  FOR  COMBINING  STEERING  AND 
DRIVING 

VI. — THE  UNDERFRAMES  OF  MOTOR  CARRIAGES 

VII. — SPRINGS,     RADIUS    RODS    AND    JOINTED 
SHAFTS 

VIII. — MOTOR  CARRIAGE  WHEELS       .... 
IX. — SOLID  RUBBER  TIRES 

X. — THE   USE  AND  EFFECT   OF   PNEUMATIC 
TIRES     

XL — CONSTRUCTION      AND      OPERATION      OF 

BRAKE'S 

XII. — ON   BALL  AND  ROLLER  BEARINGS     . 
XIII. — ON  THE  NATURE  AND  USE  OF  LUBRICANTS 

XIV. — GENERAL    PRINCIPLES    OF    GAS    ENGINE 
OPERATION 

XV. — THE  PRESSURE,  TEMPERATURE  AND  VOL- 
UME OF  GASES  IN  A  GAS  ENGINE     . 


PAGE. 

1-6 


7-18 
19-34 
35-53 

54-61 
62-79 

80-93 

94-104 

105-111 

112-145 

146-152 
153-158 
159-164 

165-177 
178-189 


i  CONTENTS. 

CHAPTER.  PAGE. 

XVI. — THE  METHODS  AND  CONDITIONS  OF  GAS 

ENGINE  CYLINDER  COOUNG  .      .      .     190-205 

XVII. — CONDITIONS  RESULTING   FROM    COMBUS- 
TION OF  THE  FUEL  CHARGE  .      .      .     206-220 

XVIII. — GAS  ENGINE  EFFICIENCY 221-231 

XIX. — ESTIMATING  THE  HORSE- POWER  OF  GAS 

ENGINES .     232-241 

XX. — ON  CARBURETTERS  AND  VAPORIZERS   .      .     242-259 
XXL — ON  THE  METHODS  OF  FIRING  THE  CHARGE     260-296 

XXII. — DEVELOPMENT  OF  GASOLINE  MOTORS  BY 

DAIMLER  AND  HIS  SUCCESSORS  .      .     297-344 

XXIII. — THE    CONSTRUCTION    AND    CONTROL    OF 

TYPICAL  GASOLINE  CARRIAGES    .      .     345-424 

XXIV. — GENERAL  PRINCIPLES  OF  ELECTRICITY     .     425-430 
XXV. — ELECTRICAL  GAUGES      ....'...     431-435 

XXVI. — CONSTRUCTION   OF  THE   DYNAMO  ELEC- 
TRICAL GENERATOR  AND  MOTOR   .      .     436-444 

XXVII. — OPERATION  OF  ELECTRICAL  GENERATORS 

AND  MOTORS     .      .     .     .      .      .     .     445-458 

XXVIII.— MOTORS   FOR   ELECTRIC   VEHICLES     .      .     459~477 
XXIX. — PRACTICAL  POINTS  ON  MOTOR  TROUBLES    478-482 

XXX. — METHODS     OF     CIRCUIT-CHANGING     IN 

ELECTRIC  VEHICLES    .     .     ...    483-495 

XXXI. — CONSTRUCTION  AND  OPERATION  OF  STOR- 
AGE BATTERIES 496-522 


.    CONTENTS.  vii 


CHAPTER. 


XXXII. — STEAM  AND  ITS  USE  AS  A  MOTIVF  POWER    523-539 

XXXIII. — CONSTRUCTION    AND    OPERATION    OF    A 

STEAM   ENGINE 540-550 

XXXIV. — SMALL   SHELL  AND  FLUE  BOILERS  FOR 

STEAM  CARRIAGES 55X~557 

XXXV.— OF  WATER  TUBE  BOILERS,  AND  THEIR 

USE  IN  STEAM  CARRIAGES     .      .      .     558-567 

XXXVI. — FLASH  STEAM  GENERATORS     ....     568-578 

XXXVII. — THE  TESTING  AND  REGULATING  ATTACH- 
MENTS OF  STEAM  BOILERS     .     .     .     579-585 

XXXVIII. — BOILER    FEEDERS    AND    WATER    LEVEL 

REGULATORS      586-595 

XXXIX. — LIQUID  FUEL  BURNERS  AND  REGULATORS    596-608 
XL. — SIMPLE  STEAM  CARRIAGE  ENGINES     .      .     609-613 

XLI. — SINGLE-ACTING    STEAM    CARRIAGE    EN- 
GINES          614-616 

XLII. — COMPOUND  STEAM  ENGINES    ....     617-629 

XLIII. — HINTS  ON  GASOLINE  VEHICLE  MANAGE- 
MENT          630-636 

XLI V.— GASOLINE  MOTOR  CYCLES 637-644 


CHAPTER    ONE. 


TYPES    AND    MERITS    OF    AUTOMOBILES. 


Types  of  Automobiles. — Within  the  iast  three  years  the  con- 
struction of  automobiles,  or  motor-propelled  road  vehicles  has 
been  greatly  modified  and  improved  in  a  number  of  particulars. 
The  troubles  that  were  previously  notable  are  now  very  nearly 
overcome,  and  in  the  case  of  steam,  electric  and  gasoline  car- 
riages alike  the  ideal  of  a  perfectly  practical  machine  is  rapidly 
being  approximated.  Neither  has  this  gradual  development  of 
the  ideal  vehicle  involved  any  such  radical  changes  as  some  super- 
ficial and  ill-informed  persons  have  confidently  predicted.  True 
to  the  statements  of  practical  experts,  the  leading  features — 
such  as  steering  and  compensating  apparatus,  rear-wheel  drive, 
resilient  tires,  and  several  other  features — have  remained  the 
same.  Only  the  details  have  been  altered  and  improved  in  the 
gradual  evolution  of  the  practical  out  of  the  experimental. 
Furthermore,  the  steady  tendency  is  toward  a  greater  uniformity 
of  design,  rather  than  toward  any  eccentric  or  novel  construc- 
tions;  toward  a  perfecting  of  standard  constructions  already 
recognized,  rather  than  toward  anything  entirely  new  and  pe- 
culiar. 

In  another  respect  the  development  of  the  practical  road  car- 
riage is  notable :  and  that  is,  that  types  formerly  prevalent  are 
gradually  lapsing  in  popularity,  while  others  are  gaining  in  cor- 
responding ratio.  Thus,  steam  carriages,  which  a  few  years  since 
were  manufactured  by  nearly  two-score  different  concerns  in  this 
country,  are  at  present  built  by  scarcely  half  that  number,  and 
are  sold  in  very  small  numbers.  The  electrical  vehicle  has  taken 
its  logical  position  as  a  means  of  freight  and  passenger  traffic  in 
cities  and  for  short  tours  out  of  town ;  while  the  gasoline  ma- 
chine is  rapidly  gaining  recognition  as  the  automobile  par  ex- 
cellence. Such  changes  in  popular  estimate  of  the  three  types  of 
driving  power  are  based  almost  entirely  upon  practical  considera- 
tions, quite  independent  of  the  arguments  that  may  be  adduced 
by  interested  authorities  and  enthusiasts.  Furthermore,  the  fore- 


2  SELF-PROPELLED   VEHICLES. 

most  considerations  in  the  mind  of  the  motor-using  public  refer 
almost  entirely  to  ease  of  care  and  control  and  immunity  from 
disablement.  This  explains  the  present  pre-eminence  of  the  gaso- 
line machine,  in  which  the  sole  requirement  for  starting  is  to 
crank  the  engine,  thus  saving  the  troubles  incident  on  starting  the 
fire,  as  in  the  steamer,  or  on  caring  for  and  recharging  the  bat- 
tery, as  in  the  electric. 

Advantages  Analyzed. — In  a  recent  number  of  a  well-known 
automobile  journal  (Motor,  New  York),  the  several  advantages 
of  the  three  types  of  machine  are  set  forth  by  prominent  experts. 

Speaking  for  the  steam  vehicle,  Windsor  T.  White  specifies 
the  following  twelve  advantages :  ( i )  Practical  absence  of  jar  and 
noise;  (2)  ease  of  control — throttling  instead  of  gear  shifting  by 
levers;  (3)  absence  of  gearing  between  the  engine  and  the  drive 
axle;  (4)  flexibility  of  the  steam  engine,  permitting  any  speed, 
from  highest  to  lowest,  with  nearly  even  power  efficiency;  (5) 
continuous  application  of  power  in  each  cylinder,  instead  of  a 
power  stroke  in  each  two  revolutions,  as  with  the  four-cycle 
gasoline  engine;  (6)  ease  of  lubrication  in  the  comparative- 
ly cool  cylinder,  and  absence  of  trouble  from  over  -  oiling ; 
(7)  the  fact  that  the  steam  engine  is  better  understood  by  the 
average  man  than  either  of  the  other  motive  powers;  (8)  from 
this  reason,  the  greater  ease  of  having  roadside  repairs  made; 
(9)  a  combination  of  flash  generator,  automatic  fuel  regula- 
tion, compound  engine  and  direct  drive  gives  the  most  satis- 
factory machine  for  inexpert  operators;  (10)  certain  and  invari- 
able automatic  regulation  dependent  solely  on  the  physical  prop- 
erties of  varying  temperature  and  pressure;  (n)  complete  elim- 
ination of  boiler  troubles,  scaling,  etc.,  by  the  use  of  the  flash 
generator;  (12)  complete  immunity  from  burning  out,  with  the 
combination  of  flash  generator  and  thermostatic  regulation. 

Mr.  White  is  speaking,  of  course,  of  a  carriage  using  the  flash- 
line  system  of  generation,  as  embodied  in  the  machines  built  by 
his  company,  which  have  proved  of  the  greatest  advantage  for 
this  purpose  since  the  time  of  Serpollet's  first  invention  of  this 
apparatus  in  1889.  With  other  types  of  generator  and  regulator 
the  advantages  are  less  conspicuous.  Mervyn  O'Gorman,  an 
English  authority,  states  the  case  of  the  average  steam  carriage 
from  both  sides.  As  ten  advantages :  ( i )  Absence  of  speed  gears ; 


TYPES   AND   MERITS   OP   AUTOMOBILES.  3 

(2)  saving  of  wear,  tear  and  noise;  (3)  high  power-outputs  for 
short  periods  for  climbing  hills  and  traveling  on  rough  roads; 
(4)  greater  speed  uphill,  and  greater  average  speed  for  original 
cost;  (5)  proportionate  fuel  consumption  and  power  efficiency ; 

(6)  cleanliness  equal  to  petrol  motors;  (7)  absence  of  the  trou- 
blesome ignition  system,  as  on  petrol  motors;    (8)    absence  of 
exhaust  noises,  back-shots,  pre-ignition,  etc. ;    (9)   cheapness  in 
first  cost;   (10)   starting  without  cranking,  therefore  stillness  of 
the  car  in  standing.     As  sixteen  disadvantages  :  ( I )  The  need  of 
extinguishing    the    fire    during    stoppages;    (2)    the    consequent 
trouble  of  re-igniting  the  burner  5(3)  the  great  loss  of  fuel,  due  to 
not  extinguishing;  (4)  the  need  for  greater  attention,  owing  to 
the  number  of  adjustments  not  automatic;   (5)   limited  capacity 
for  carrying  fuel  and  water  supply;  (6)  heavy  fuel  consumption, 
generally  twice  that  of  gasoline  carriages  of  the  same  power; 

(7)  heavy  water  consumption,  and  the  need  for  constant  refills; 

(8)  fouling  of  the  boiler  tubes — in  some  types ;  (9)  vitiation  of 
the  air  by  burned  products  in  greater  volume  than  with  gasoline 
motors;   (10)   loss  of  time  in  starting  from  a  cold  boiler;  (n) 
greater  dangers  from  neglect,  such  as  seizing  and  heating  from 
insufficient  lubrication,  grave  consequences  in   failure  of  water 
system,  priming  from  high  water  and  consequent  knocking  of 
the  pistons,  evil  effects  of  feeding  oil  into  any  type  of  boiler  or 
generator,   clogging   of   valves   or   failure   of  pumps;    (12)    the 
troubles,  due  to  wind  blowing  down  upon  the  fire;  (13)  stoppage 
of  safety  valves;  (14)  necessity  of  using  soft  water  for  boilers; 
(15)   trouble  of  cleaning  the  flues;   (16)   issue  of  visible  steam 
mixed  with  oil  liable  to  stain  clothes. 

Setting  forth  the  advantages  of  the  gasoline  carriage,  Elmer 
Apperson  enumerates  the  following  twelve  points :  ( I )  Availa- 
bility of  fuel,  readily  obtainable  anywhere;  (2)- convenience  in 
renewing  the  supply,  no  fire  being  present  that  must  be  extin- 
guished;  (3)  economy  of  fuel,  owing  (a)  to  none  being  used 
when  the  machine  is  standing,  (b)  to  the  small  amount  used  when 
running  light,  (c)  to  the  high  efficiency  of  the  gasoline  engine 
— twenty-five  or  thirty  per  cent,  as  against  ten  per  cent,  for  the 
steam  engine,  and  less  for  the  electric  motor;  (4)  perfect  throt- 
tling system  for  changing  the  speed  and  power  ratios;  (5)  noise- 
lessness,  as  achieved  in  the  later  types  of  motor ;  (6)  ease  of  using- 
in  winter  with  non-freezing  jacket  solutions;  (7)  the  absence  of 


4  SELF-PROPELLED   VEHICLES. 

indicating  devices  to  distract  the  rnind  of  the  operator;  (8)  ab- 
sence of  constant  fire,  as  in  a  steam  machine  to  "make  a  volcano 
of  the  slightest  leak"  ;  (9)  rareness  of  total  disablement,  as  against 
steam  or  gasoline  machines ;  ( 10)  extended  travel  radius,  gasoline 
machines  having  been  run  1,000  miles  without  a  stop,  as  against 
the  record  of  100  miles  for  a  steamer,  and  the  average  of  30  or 
40  miles  per  charge  for  the  electric ;  ( 1 1 )  the  greater  perfection 
of  the  gasoline  machine,  on  account  of  the  thought  and  labor 
expended  in  its  development;  (12)  that  it  can  be  built  with  any 
style  of  body,  for  any  kind  of  service,  and  holds  all  records  for 
speed  and  endurance. 

The  claims  of  the  electric  carriage  are  set  forth  by  Walter  C. 
Baker  under  the  following  twelve  heads :  ( i )  The  superior  ma- 
terial of  the  electric  carriage,  together  with  its  durability  and 
attractiveness ;  ( 2 )  the  speed  range,  greater  than  a  horse  at  low 
speed  and  within  legal  limits  at  top  speed;  (3)  the  small  care 
required  in  comparison  with  other  types  of  power,  the  smallest 
attention  yielding  the  best  results — the  battery  alone  demanding 
particular  care  5(4)  the  ideal  source  of  energy  found  in  the  stor- 
age battery,  which  is  compact,  clean,  safe,  and  able  to  yield  in- 
stantly to  the  will  of  the  operator;  (5)  freedom  from  noise,  odor 
or  vibration;  (6)  with  all  mechanical  parts  rotating,  anti-friction 
bearings  may  be  used  throughout,  enabling  great  results  from 
little  power;  (7)  the  slight  physical  effort  required  to  manage 
it;  (8)  absence  of  oil,  fire,  water  and  pumps  leaves  nothing  to 
freeze,  burn,  or  explode,  and  requires  no  pumping  at  the  start; 
(9)  absence  of  lubricants  renders  it  clean ;  ( 10)  safety  for  ladies 
and  convenience  for  short  tours ;  ( 1 1 )  small  number  of  occasions 
for  failure  to  run  ;  (12)  a  single  lever  to  control  the  motive  power, 
and  another  for  steering,  rendering  it  the  simplest  of  all  to  man- 
age. 

While,  strangely  enough,  all  the  statements  made  above  are  per- 
fectly true  and  undeniable,  it  must  still  be  maintained  that  there 
is 'a  very  real  and  radical  difference  in  the  serviceability  of  the 
several  types  of  motor  vehicles.  Could  an  electric  carriage  be 
constructed  with  a  travel  radius  per  charge  of  battery  of  TOO  or 
150  miles,  it  would  undoubtedly  be  the  ideal  type  for  amateurs 
on  short  tours.  At  present  its  limited  possibilities  curtail  its  use- 
fulness. A  steam  carriage,  equipped  with  a  flash  generator  and  a 
strongly  constructed  compact  engine  is  equally  useful.  But  at 


TYPBS   AND   MERITS   OF  AUTOMOBILES. 


STEAM    RUNABOUT. 


ELECTRIC    VICTORIA 


ELECTRIC    COUPE. 


ELECTRIC    STANHOPE. 


TOURING    CAR. 


STEAM     SURREY. 


RACING    CA*.>  CiASOLINF    VOITURETTE. 

FIGS.  1-8.— Eight  Familiar  Types  of  Self-Propelled  Road  Vehicles. 


(5  SELF-PROPELLED   VEHICLES. 

the  present  time  very  many  makes  of  steam  carriages  fail  on  ac- 
count of  the  bewildering  complications  which  none  but  close 
students  can  fully  master.  As  for  the  statement  that  the  steam 
engine  is  more  lamiliar  to  the  average  mind,  that  must  be  taken 
with  reservation,  rx  century  of  discussion  and  explanation  has 
rendered  the  steam  engine  more  familiar  in  its  broad  and  general 
principles,  but  uie  average  mind  is  densely  ignorant  of  its  essen- 
tial details,  and  completely  lost  in  the  presence  of  the  practical 
problems  f  operation.  In  this  respect  the  gasoline  engine  cer- 
tainly has  the  advantage.  Its  principles  once  understood,  and 
the  few  common  causes  of  failure  explained,  there  is  little  that 
the  amateur  needs  to  know  further. 

At  best,  very  few  people  who  own  and  operate  motor  vehicles 
care  to  delve  into  the  mysteries  of  construction  and  the  mazes  of 
theory.  The  machine  that  can  be  operated  with  the  least  care,  in 
return  for  the  greatest  service,  in  horse  power,  travel  compass  and 
speed,  is  the  one  that  is  bound  to  prevail  in  the  end. 


CHAPTER   TWO. 

A   BRIEF   HISTORY   OF   SELF-PROPELLED   ROAD   VEHICLES. 

Requirements    for    a     Successful    flotor    Carriage.— Even 

before  the  days  of  successful  railroad  locomotives  several  in- 
ventors had  proposed  to  themselves  the  problem  of  a  steam- 
propelled  road  wagon,  and  actually  made  attempts  to  build  ma- 
chines to  embody  their  designs.  In  1769  Nicholas  Joseph 
Cugnot,  a  captain  in  the  French  army,  constructed  a  three- 
wheeled  wagon,  having  the  boiler  and  engine  overhanging,  and 
to  be  turned  "with  the  forward  wheel,  and  propelled  by  a  pair  of 
single-acting  cylinders,  which  worked  on  ratchets  geared  to  the 
axle  shaft.  It  was  immensely  heavy,  awkward  and  unmanageable, 
but  succeeded  in  making  the  rather  unexpected  record  of  two  and 
a  half  miles  per  hour,  over  the  wretched  roads  of  that  day,  despite 
the  fact  that  it  must  stop  every  few  hundred  feet  to  steam  up.  Later 
attempts  in  the  same  direction  introduced  several  of  the  essential 
motor  vehicle  parts  used  at  the  present  day,  and  with  commen- 
surately  good  results.  But  the  really  practical  road  carriage  can- 
not be  said  to  have  existed  until  inventors  grasped  the  idea  that 
the  fuel  for  the  engines  must  be  something  other  than  coal,  and 
that,  so  far  as  the  boilers  and  driving  gears  are  concerned,  the 
minimum  of  lightness  and  compactness  must  somehow  be  com- 
bined with  the  maximum  of  power  and  speed.  This  seems  a  very 
simple  problem,  but  we  must  recollect  that  even  the  simplest 
results  are  often  the  hardest  to  attain.  Just  as  the  art  cf  printing 
dates  from  the  invention  of  an  inexpensive  method  of  making 
paper,  so  light  vehicle  motors  were  first  made  possible  by  the 
successful  production  of  liquid  or  volatile  fuels. 

In  addition  to  this,  as  we  shall  presently  understand,  immense 
contributions  to  the  present  successful  issue  have  been  made  by 
pneumatic  tires,  stud  steering  axles  and  balance  gears,  none  of 
which  were  used  in  the  motor  carriages  of  sixty  and  eighty  years 
ago.  So  that,  we  may  confidently  insist,  although  many  thought- 
less persons  still  assert  that  the  motor  carriage  industry  is  in  its 
infancy,  and  its  results  tentative,  we  have  already  most  of  the 

7 


8  SELF-PROPELLED   VEHICLES. 

elements  of  the  perfect  machine,  and  approximations  of  the  re- 
mainder. At  the  present  time  the  problem  is  not  on  what  ma- 
chine can  do  the  required  work,  but  which  one  can  do  it  best. 

A  Brief  Review  of  Motor  Carriage  History. — As  might  be 
readily  surmised,  the  earliest  motor  vehicles  were  those  propelled 
by  steam  engines,  the  first  attempt,  that  of  Capt.  Cugnot,  dating, 
as  we  have  seen,  from  1769-70.  In  the  early  years  of  the  nine- 
teenth century,  and  until  about  1840-45,  a  large  number  of  steam 


*IG.  9.-Captain  Cugnot 's  Three-wheel  Steam  Artillery  Carriage  (1769-70).    This  cut  shows 
details  of  the  single  flue  boiler  and  of  the  driving  connections. 

carriages  and  stage  coaches  were  designed  and  built  in  England, 
some  of  them  enjoying  considerable  success  and  bringing  profit 
to  their  owners.  At  about  the  close  of  this  period,  however,  strict 
laws  regarding  the  reservation  of  highways  to  horse-vehicles  put 
an  effectual  stop  to  the  further  progress  of  an  industry  that  was 
already  well  on  its  way  to  perfection,  and  for  over  forty  years 
little  was  done,  either  in  Europe  or  America,  beyond  improving 
the  type  of  farm  tractors  and  steam  road  rollers,  with  one  or  two 
sporadic  attempts  to  introduce  self-propelling  steam  fire  engines. 
During  the  whole  of  this  period  the  light  steam  road  carriage 
existed  only  as  a  pet  hobby  of  ambitious  inventors,  or  as  a  curi- 
osity for  exhibition  purposes.  Curiously  enough,  while  the 
progress  of  railroad  locomotion  was,  in  the  meantime,  rapid  and 
brilliant,  the  re-awakening  of  the  motor  carriage  idea  and  in- 
dustry, about  1885-89,  was  really  the  birth  of  a  new  science  of 
constructions,  very  few  of  the  features  of  former  carriages  being 
then  adopted.  In  1885  Gottlieb  Daimler  patented  his  high-speed 
gas  or  mineral  spirit  engine,  the  parent  and  prototype  of  the  wide 


MOTOR    VEHICLE  HISTORY. 


9 


variety  of  explosive  vehicle  motors  since  produced,  and,  in  the 
same  year,  Carl  Benz,  of  Mannheim,  constructed  and  patented 
his  first  gasoline  tricycles.  The  next  period  of  progress,  in  the 
years  immediately  succeeding,  saw  the  ascendency  of  French 
engineers,  Peugeot,  Panhard,  De  Dion  and  Mors,  whose 
names,  next  to  that  of  Daimler  himself,  have  become  common- 
places with  all  who  speak  of  motor  carriages.  In  1889  Leon 
Serpollet,  of  Paris,  invented  his  famous  instantaneous,  or  "flash," 
generator,  which  was,  fairly  enough,  the  most  potent  agent  in 
restoring  the  steam  engine  to  consideration  as  means  of  motor 


FIG.  10.— Richard  Trevithick's  Steam  Road  Carriage  (1802).  The  centre-pivoted  front 
axle  is  about  half  the  length  of  the  rear  axle.  The  cylinder  is  fixed  in  the  centre  of 
the  boiler.  The  engine  has  a  fly-wheel  and  spur  gear  connections  to  the  drive  axle. 

carriage  propulsion.  Although  it  has  not  become  the  prevailing 
type  of  steam  generator  for  this  purpose,  it  did  much  to  turn  the 
attention  of  engineers  to  the  work  of  designing  high-power, 
quick-steaming,  small-sized  boilers,  which  have  been  brought  to 
such  high  efficiency,  particularly  in  the  United  States.  With 
perfected  steam  generators  came  also  the  various  forms  of  liquid 
or  gas  fuel  burners.  The  successful  electric  carriage  dates  from 
a  few  years  later  than  either  of  the  others,  making  its  appearance 
as  a  practical  permanency  about  1893-94. 

Trevithick's  Steam  Carriage. — In  reviewing  the  history  of 
motor  road  vehicles  we  will  discover  the  fact  that  the  attempts 
which  were  never  more  than  plans  on  paper,  working  models,  or 
downright  failures  are  greatly  in  excess  of  the  ones  even  half- 


10  SELF-PROPELLED    VEHICLES. 

way  practical.  From  within  a  few  years  after  Cugnot's  notable 
attempt  and  failure,  many  inventors  in  England,  France  and 
America  appeared  as  sponsors  for  some  kind  of  a  steam  road  car- 
riage, and  as  invariably  contributed  little  to  the  practical  solution 
of  the  problem.  In  1802  Richard  Trevithick,  an  engineer  of  abil- 
ity, subsequently  active  in  the  work  of  developing  railroad  cars 
and  locomotives,  built  a  steam-propelled  road  carriage,  which, 
if  we  may  judge  from  the  drawings  and  plans  still  extant,  was 
altogether  unique,  both  in  design  and  operation.  The  body  was 
supported  fully  six  feet  from  the  ground,  above  rear  driving 
wheels  of  from  eight  to  ten  feet  in  diameter,  which,  turning  loose 
on  the  axle  trees,  were  propelled  by  spur  gears  secured  to  the 
hubs.  The  cylinder  placed  in  the  centre  of  the  boiler  turned  its 
crank  on  the  counter-shaft,  just  forward  of  the  axle,  and  imparted 
its  motion  through  a  second  pair  of  spur  gears,  meshing  with 
those  attached  to  the  wheel  hubs.  The  steering  was  by  the  for- 
ward wheels,  whose  axle  was  about  half  the  width  of  the  vehicle, 
and  centre-pivoted,  so  as  to  be  actuated  by  a  hand  lever  rising 
in  front  of  the  driver's  seat.  This  difference  in  the  length  of  the 
two  axles  was  probably  a  great  advantage  to  positive  steering 
qualities,  even  in  the  absence  of  any  kind  of  compensating  device 
on  the  drive  shaft.  The  carriage  was  a  failure,  however,  owing 
to  lack  of  financial  support,  as  is  alleged,  and,  after  a  few  trial 
runs  about  London,  was  finally  dismantled. 

Gurney's  Coaches. — The  Golden  Age  of  steam  coaches  ex- 
tended from  the  early  twenties  of  the  nineteenth  century  for  about 
twenty  years.  During  this  period  much  was  done  to  demonstrate 
the  practicability  of  steam  road  carriages,  which  for  a  time 
seemed  promising  rivals  to  the  budding  railroad  industry.  Con- 
siderable capital  was  invested  and  a  number  of  carriages  were 
built,  which  actually  carried  thousands  of  passengers  over  the  old 
stage-coach  roads,  until  adverse  legislation  set  an  abrupt  period 
to  further  extension  of  the  enterprise.  Among  the  names  made 
prominent  in  these  years  is  that  of  Goldsworthy  Gurney,  who,  in 
association  with  a  certain  Sir  Charles  Dance,  also  an  engineer, 
constructed  several  coaches,  which  enjoyed  a  brief  though  suc- 
cessful career.  His  boiler,  like  those  then  used  in  the  majority 
of  carriages,  was  of  the  water-tube  variety,  and  in  many  respects 


MOTOR    VEHICLE  Iff  STORY. 


11 


closely  resembled  some  of  the  most  successful  styles  made  at  the 
present  day.  It  consisted  of  two  parallel  horizontal  cylindrical 
drums,  set  one  above  the  other  in  the  width  of  the  carriage,  sur- 
mounted by  a  third,  a  separator  tube,  and  connected  together 
by  a  number  of  tubes,  each  shaped  like  the  letter  U  laid  on  its 
side,  and  also,  directly,  by  several  vertical  tubes.  The  fire  was 
applied  to  the  lower  sides  of  the  bent  tubes,  under  forced  draught, 
thus  creating  a  circulation,  but,  on  account  of  the  small  heating 
surface,  the  boiler  was  largely  a  failure.  Mr.  Dance  did  much 

A 


Flo.  11.— Sectional  Elevation  ot  one  of  Goldsworthy  Gurney's  Early  Coaches,  showing 
water  tube  boiler,  directly  geared  cylinders  and  peg-rod  driving  wheel. 

to  remedy  the  defects  of  Gurney's  boiler  with  a  water-tube  gen- 
erator, designed  by  himself,  in  which  the  triple  rows  of  parallel 
U-tubes  were  replaced  by  a  number  of  similarly-shaped  -tubes 
connected  around  a  common  circumference  by  elbow  joints,  and 
surmounted  by  dry  steam  tubes,  thus  affording  a  much  larger 
heating  surface  for  the  fire  kindled  above  the  lower  sides  of  the 
bent  tubes.  Gurney's  engine  consisted  of  two  parallel  cylinders, 
fixed  in  the  length  of  the  carriage  and  operating  cranks  on  the 
revolving  rear  axle  shaft.  The  wheels  turned  loose  on  the  axles, 
and  were  driven  by  double  arms  extending  in  both  directions 


12 


SELF-PROPELLED    VEHICLES. 


from  the  axle  to  the  felloe  of  the  wheel,  where  they  engaged  suit- 
ably arranged  bolts,  or  plugs.  On  level  roadways  only  one  wheel 
was  driven,  in  order  to  allow  of  turning,  but  in  ascending  hills 
both  were  geared  to  the  motor,  thus  giving  full  power.  In  Gur- 
ney's  later  coaches  and  tractors  the  steering  was  by  a  sector, 

4- 


Fio.  12. 


Fio.  13. 


FIGS.  12-13.— Improved  Boilers  for  Qurney  Coaches  ;  the  first  by  Summers  &  Ogle  ;  the 
second  by  Maceroni  &  Squire. 

with  its  centre  on  the  pivot  of  the  swinging  axle  shaft  and  oper- 
ated by  a  gear  wheel  at  the  end  of  the  revolving  steering  post.  In 
one  of  his  earliest  carriages  he  attempted  the  result  with  an  extra 
wheel  forward  of  the  body  and  the  four-wheel  running  frame, 
the  swinging  forward  axle  being  omitted,  but  this  arrangement 
speedily  proving  useless,  was  abandoned. 

Improvements  on  Gurney's  Coaches. — Several  other  builders, 
notably  Maceroni  and  Squire,  and  Summers  and  Ogle,  adopted 
the  general  plans  of  Gurney's  coaches  and  driving  gear,  but 
added  improvements  of  their  own  in  the  construction  of  the 
boilers  and  running  gear.  The  former  partners  used  a  water- 
tube  boiler  consisting  of  eighty  vertical  tubes,  all  but  eighteen 
of  which  were  connected  at  top  and  bottom  by  elbows  or  stay- 
tubes,  the  others  being  extended  so  as  to  communicate  with  a 


MOTOR   V&MCLE 

Central  vertical  steam  drum.  Summers  and  Ogle's  boiler  con- 
sisted of  thirty  combined  water  tubes  and  smoke  flues,  fitting 
into  square  plan,  flat  vertical-axis  drums  at  top  and  bottom.  Into 
each  of  these  drums — the  one  for  water,  the  other  for  steam — the 
water  tubes  opened,  while  through  the  top  and  bottom  plates, 
through  the  length  of  the  water-tubes,  ran  the  contained  smoke 
flues,  leading  the  products  of  combustion  upward  from  the  fur- 
nace. The  advantage  of  this  construction  was  that  considerable 
water  could  be  thus  heated,  under  draught,  in  small  tube  sec- 
tions, while  the  full  effect  of  250  square  feet  of  heating  surface 
was  realized.  With  both  these  boilers  exceedingly  good  results 
were  obtained,  both  in  efficiency  and  in  small  cost  of  operation. 
Indeed,  the  reasonable  cost  of  running  these  old-time  steam  car- 
riages is  surprising.  It  has  been  stated  that  Gurney  and  Dance's 
coaches  required  on  an  average  about  4d.  (eight  cents)  per  mile 
for  fuel  coke,  while  the  coaches  built  by  Maceroni  and  Squire 
often  averaged  as  low  as  3d.  (six  cents).  The  average  weight  of 
the  eight  and  ten-passenger  coaches  was  nearly  5,000  pounds, 
their  speed,  between  ten  and  thirty  miles,  and  the  steam  pressure 
used  about  200  pounds. 

Hancock's  Coaches. — By  all  odds  the  most  brilliant  record 
among  the  early  builders  of  steam  road  carriages  is  that  of  Walter 
Hancock,  who,  between  the  years  1828  and  1838,  built  nine  car- 
riages, six  of  them  having  seen  actual  use  in  the  work  of  carrying 
passengers.  His  first  effort,  a  three-wheeled  phaeton,  was  driven 
by  a  pair  of  oscillating  cylinders  geared  direct  to  the  front  wheel, 
and  being  turned  on  the  frame  with  it  in  steering.  Having 
learned  by  actual  experiment  the  faults  of  this  construction,  he 
adopted  the  most  approved  practice  of  driving  on  the  rear  axle, 
and  in  his  first  passenger  coach,  "The  Infant,"  he  attached  his 
oscillating  cylinder  at  the  rear  of  the  frame,  and  transmitted  the 
power  by  an  ordinary  flat-link  chain  to  the  rotating  axle.  He 
was  the  first  to  use  the  chain  transmission,  now  practically  uni- 
versal. As  he  seems  to  have  been  a  person  who  readily  learned 
by  experience,  he  soon  saw  that  the  exposure  of  his  engines  to 
dust  and  other  abradents  was  a  great  source  of  wear  and  disable- 
ment; consequently  in  his  second  coach,  "Infant  No.  2,"  he  sup- 
planted the  oscillating  cylinder  hung  outside  by  a  slide-valve 


14 


SELF-PROPELLED    VEHICLES. 


cylinder  and  crank  disposed  within  the  rear  of  the  coach  body 
above  the  floor.  In  this  and  subsequent  carriages  he  used  the 
chain  drive,  also  operating  the  boiler  feed  pump  from  the  cross- 
head,  as  in  most  steam  carriages  at  the  present  day. 

Hancock's  boiler  was  certainly  the  most  interesting  feature  of 
his  carriages,  both  in  point  of  original  conception  and  efficiency 
in  steaming.  It  was  composed  of  a  number  of  flat  chambers — 
"water  bags"  they  were  called — laid  side  by  side  and  intercom- 
municating with  a  water  drum  at  the  base  and  steam  drum  at 
the  top.  Each  of  these  chambers  was  constructed  from  a  flat 
sheet  of  metal,  hammered  into  the  required  shape  and  flanged 
along  the  edges,  and,  being  folded  together  at  the  middle  point, 


FIG.  14.— Part  section  of  one  of  Hancock's  Coaches,  showing  Engine  and  Driving  Connec- 
tions. A  is  the  exhaust  pipe  leading  steam  against  the  screen,  C,  thence  up  the  flue, 
D,  along  with  smoke  and  gases  from  the  grate,  B.  E  is  the  boiler;  H  the  out-take 
pipe;  K  the  engine  cylinder  and,  J,  the  water-feed  pump;  G  is  a  rotary  fan  for  produc- 
ing a  forced  draught,- and  F  the  flue  leading  it  to  the  grate. 

the  two  halves  were  securely  riveted  together  through  the 
flanged  edge.  The  faces  of  each  plate  carried  regularly  disposed 
hemispherical  cavities  or  bosses,  which  were  in  contact  when  the 
plates  were  laid  together,  thus  preserving  the  distances  between 
them  and  allowing  space  for  the  gases  of  combustion  to  pass  over 
an  extended  heating  surface.  The  high  quality  of  this  style  of 
generator  may  be  understood  when  we  learn  that,  with  eleven 
such  chambers  or  "water  bags,"  30  x  20  inches  x  2  inches  in 
thickness  and  89  square  feet  of  heating  surface  to  6  square  feet 
of  grate,  one  effective  horse-power  to  every  five  square  feet  was 


MOTOR    VEHICLE  HISTORY. 


15 


realized,  which  gives  us  about  eighteen  effective  horse-power 
for  a  generator  occupying  about  n.i  cubic  feet  of  space,  or  30  x 
20  x  32  inches. 

The  operation  of  the  Hancock  boiler  is  interesting.  The  most 
approved  construction  was  to  place  the  grate  slightly  to  the  rear 
of  the  boiler's  centre,  and  the  fuel,  coke,  was  burnt  under  forced 
draught  from  a  rotary  fan.  The  exhaust  steam  was  forced  into 
the  space  below  the  boiler,  where  a  good  part  of  it,  passing 
through  a  finely  perforated  screen,  was  transformed  into  water 
gas,  greatly  to  the  benefit  of  perfect  combustion. 


) 

) 


FIG.  15. 


FIG  16. 


FIG.  15.— Hancock's  Wedge  Drive  Wheel,  showing  wedge  spokes  and  triangular  driving 

lugs  at  the  nave. 
FIG.  16.— One  element  of  the  Hancock  Boiler,  end  view. 

As  early  as  1830  Hancock  devised  the  "wedge"  wheels,  since 
so  widely  adopted  as  models  of  construction.  As  shown  in  the 
accompanying  diagram,  his  spokes  were  formed,  each  with  a 
blunt  wedge  at  its  end,  tapering  on  two  radii  from  the  nave  of  the 
wheel;  so  that,  when  laid  together,  the  shape  of  the  complete 
wheel  was  found.  The  blunt  ends  of  these  juxtaposed  wedges 
rested  upon  the  periphery  of  the  axle  box,  which  carried  a  flange, 


SELF-PROPELLED 


or  vertical  disk,  forged  in  one  piece  with  it,  so  as  to  rest  on  th€ 
inside  face  of  the  wheel.  This  flange  was  pierced  at  intervals  to 
hold  bolts,  each  penetrating  one  of  the  spokes,  and  forming  the 
"hub"  with  a  plate  of  corresponding  diameter  nutted  upon  the 
outer  face  of  the  wheel.  The  through  axle  shaft,  formed  in  one  piece 
and  rotatable,  carried  secured  to  its  extremities,  when  the  wheel 
was  set  in  place,  two  triangular  lugs,  oppositely  disposed  and 
formed  on  radii  from  the  nave.  The  outer  hub-plate  carried 


Fio.  17.— Church's  Three-wheel  Coach  (1833),  drawn  from  an  old  woodcut,  showing  for- 
ward spring  wheel  mounted  on  the  steering  pivot. 

similarly  shaped  and  disposed  lugs,  and  the  driving  was  effected 
by  the  former  pair,  turning  with  the  axle  spindle,  engaging  the 
latter  pair,  thus  combining  the  advantages  of  a  loose-turning 
wheel  and  a  rotating  axle.  Through  nearly  half  of  a  revolution  also 
the  wheel  was  free  to  act  as  a  pivot  in  turning  the  wagon,  thus 
obtaining  the  same  effect  as  with  Gurney's  arm  and  pin  drive 
wheels.  The  prime  advantage,  however,  was  that  the  torsional 
strain  was  evenly  distributed  through  the  entire  structure  by 
virtue  of  the  contact  of  the  spoke  extremities. 


MOTOX   KEtftCLM 

Other  Notable  Coaches. — According  to  several  authorities, 
only  Gurney,  Hancock  and  J.  Scott  Russell  built  coaches  that 
saw  even  short  service  as  paying  passenger  conveyances — one  of 
the  latter's  coaches  was  operated  occasionally  until  about  1857. 
There  were,  however,  numerous  attempts  and  experimental  struc- 
tures, all  more  or  less  successful,  which  deserve  passing  mention 
as  embodying  some  one  or  another  feature  that  has  become  a 
permanence  in  motor  road  carriages  or  devices  suggestive  of  such 
features.  A  coach  built  by  a  man  named  James,  about  1829,  was 
the  first  on  record  to  embody  a  really  mechanical  device  for  al- 


•Y; 


FIG.  18.— James'  Coach  (1829),  the  "  first  really  practical  steam  carriage  built."    Drawn 

from  an  old  wood  cut. 

lowing  differential  action  of  the  rear,  or  driving,  wheels.  Instead 
of  driving  on  but  one  wheel,  as  did  Gurney,  or  using  clutches, 
like  some  others,  he  used  separate  axles  and  four  cylinders,  two 
for  each  wheel,  thus  permitting  them  to  be  driven  at  different 
speeds.  This  one  feature  entitles  his  coach  to  description  as  the 
"first  really  practical  steam  carriage  built."  Most  of  the  others, 
if  the  extant  details  are  at  all  correct,  must  have  been,  except  on 
straight  roads,  exceedingly  unsatisfactory  machines  at  best.  Ac- 
cording to  the  best  information  on  the  subject,  a  certain  Hills, 
of  Deptford,  was  the  first  to  design  and  use  on  a  carriage,  in  1843, 
the  compensating  balance  gear,  or  "jack  in  the  box,"  as  it  was 
then  called,  which  has  since  come  into  universal  use  on  motor 
vehicles  of  all  descriptions.  As  for  rubber  tires,  although  a 
certain  Thompson  is  credited  with  devising  some  sort  of  inflat- 
able device  of  this  description  about  1840-45,  there  seems  to  have 


18  SELF-PROPELLED   VEHICLES. 

been  little  done  in  the  way  of  providing  a  springy,  or  resilient, 
support  for  the  wheels.  We  have,  however,  some  suggestion  of 
an  attempt  at  spring  wheels  on  Church's  coach,  which  was  built 
in  1833.  According  to  an  article  in  the  Mechanics'  Magazine  for 
January,  1834,  which  gives  the  view  of  this  conveyance,  herewith 
reproduced,  "The  spokes  of  the  wheels  are  so  constructed  as  to 
operate  like  springs  to  the  whole  machine — that  is,  to  give  and 
take  according  to  the  inequalities  of  the  road."  In  other  respects 
the  vehicle  seems  to  have  been  fully  up  to  the  times,  but,  judg- 
ing from  its  size  and  passenger  capacity,  as  shown  in  the  cut, 
it  is  reasonable  to  suppose  that  the  use  of  spring  wheels  was  no 
superfluous  ornamentation.  If  we  may  judge  further  from  the 
cut,  the  wheels  had  very  broad  tires,  thus  furnishing  another  ele- 
ment in  the  direction  of  easy  riding  on  rough  roads. 


CHAPTER  THREE. 

HOW  A  MOTOR  CARRIAGE  TURNS. 

Modern    Motor     Vehicles Like    other    achievements    of 

modern  science  and  industry,  the  motor  vehicle  is  the  resultant 
of  a  long  series  of  brilliant  inventions  and  improvements  in 
several  directions.  Successful  motor  carriages,  as  now  con- 
structed, are  of  three  varieties,  according  to  the  motive  power 
employed:  those  propelled  by  steam;  those  propelled  by  ex- 
plosive motors,  gas  or  oil  engines ;  those  propelled  by  electricity. 
Considerable  has  also  been  done  in  the  direction  of  producing 
efficient  compressed  air  motors,  which  have  been  actually  applied 
to  the  propulsion  of  heavy  road  wagons  and  street  railway  cars, 
but  for  light  carriage  service  small  results  have  thus  far  been  at- 
tained. Some  inventors  have  expended  their  energies  in  other 
directions,  and  several  patents  have  been  granted  in  the  United 
States  for  coiled  spring  and  clockwork  motors,  and  even  for 
carriages  carrying  masts  and  sails.  We  are  not  concerned,  how- 
ever, with  such  eccentric  devices;  the  aim  of  this  book  being 
merely  the  discussion  and  explanation  of  successful,  practical 
methods  actually  applied  in  the  construction  and  operation  of 
light  motor  carriages. 

Conditions    of    Automobile   Construction. — In  one  way  the 

automobile  has  a  history  very  like  that  of  the  railway  carriage. 
At  the  first  inception  both  were  devised  as  suitable  substitutes 
for  the  horse-drawn  vehicle,  and,  as  a  consequence,  began  by 
following  certain  traditions  of  construction,  which  have  proved 
very  like  hindrances  to  progress.  The  first  railway  passenger 
coaches  were  no  more  nor  less  than  ordinary  road  wagons,  several 
being  coupled  together,  so  as  to  be  drawn  along  a  grooved  tram- 
way. Later,  with  the  introduction  of  flanged  wheels  and  heavier 
constructions,  a  number  of  carriage  bodies  were  mounted  on  the 
same  running  trucks,  which  gave  the  familiar  compartment 
coaches  with  vis-a-vis  seats,  still  used  in  England  and  most  of  the 
countries  of  Continental  Europe.  Only  when  the  theory  of 

19 


20  SBLfrPROPELLED    VEHICLES. 

railway  car  construction  departed  entirely  from  the  models  and 
traditions  of  road  wagons  in  the  invention  and  adoption  of  the 
American  passenger  coach,  did  the  day  of  real  progress  and  com- 
fortable travel  begin.  In  similar  fashion,  it  may  be  safely  as- 
serted, many  of  the  greatest  constructional  problems  of  auto- 
mobiles are  to  be  traced  to  the  tradition  of  building  motor  car- 
riages as  nearly  like  horse-drawn  vehicles  as  possible.  It  seems 
that  the  most  popular  designs  of  such  vehicles  are  those  which 
appear  to  be  horse-carriages  in  all  respects  except  that  they  lack 
the  ordinary  shafts  or  poles  for  hitching  the  horses.  These 


Pio.  19.— Early  American  Railroad  Train  (1834),  showing  passenger  coaches,  which  are 

simply  transformed  road  stages. 

structural  problems  are,  however,  real  problems,  and  with  both 
railway  coaches  and  automobiles  the  adoption  of  traditional 
models  has  been  only  the  following  of  the  best  available  designs. 

Problems  in  Automobile  Construction. —  In  a  horse-drawn 
vehicle  the  tractive  power,  the  harnessed  horse,  is  applied  at  the 
front  and  is  separate  from  the  carriage  or  wagon  itself.  There- 
fore, the  only  thing  needful  is  to  so  construct  the  frame  and  run- 
ning gear  as  to  offer  the  smallest  resistance  either  in  straight- 
ahead  travel  or  turning.  As  is  well  known,  each  running  wheel 
of  a  horse  carriage  is  made  with  a  pierced  hub  and  hollow  axle 
box  or  bearing,  so  as  to  be  slipped  over  the  end  of  the  axle-bar 
and  secured  in  place  by  a  nut.  The  axle-bar  of  the  rear  wheels  is 
continuous  and  rigid  with  the  frame,  being  attached  to  the  springs 


HOW  A    MOTOR    CARRIAGE    TURNS. 


21 


supporting  the  body.  The  axle-bar  of  the  forward  wheels  is  also 
continuous  from  side  to  side,  but,  instead  of  being  bolted  to  the 
rest  of  the  frame,  is  geared  to  a  structure  commonly  called  the 
"fifth  wheel,"  a  horizontal  flat  wheel  or  "circle  iron,"  secured  to 
the  base  of  the  forward  spring,  and  sliding  on  another  similar 
segment  on  the  top  of  the  axletree ;  the  two  being  pivot-bolted  at 
the  centre,  so  as  to  allow  the  forward  wheels  to  "cut  under"  the 
vehicle,  and  turn  the  wagon  on  any  radius  its  length  and  weight 
will  permit.  Were  it  practicable  in  all  cases  to  apply  the  motive 
power  to  the  pivoted-axle  forward  wheels,  this  same  plan  of  con- 
struction would  be  as  good  for  automobiles  as  for  horse  carriages. 


Fio.  20.— A  Mechanical  Horse— the  Carmont  Tractor— Intended  to  be  attached  to  any 
form  of  horse-drawn  vehicle  at  the  turn-table,  or  "  fifth  wheel."  It  is  steered  by  its 
rear  wheels  and  drives  on  the  forward  pair. 

But  such  a  thing  is  impossible  unless  we  employ  either  a  separate 
motor  truck — a  mechanical  horse,  in  fact — or  some  yet  undis- 
covered method  of  power-transmission  gear.  This  is  the  first 
constructional  problem,  and  a  moment's  serious  reflection  will 
reveal  the  involved  difficulties. 

Imitations  of  Horse  Traction.  —  Curiously  enough,  in  the 
very  first  road  locomotive  ever  made — that  of  Nicholas  Cugnot — 
a  desperate  attempt  was  made  to  meet  and  solve  the  difficulty  of 
combining  power-traction  with  free  turning  attachments.  As 
we  have  learned,  Captain  Cugnot  employed  a  single  pivoted 
forward  wheel,  which  was  geared  rigid  to  one  frame  with  his 
engine  and  boiler,  the  whole  motor-structure  turning  with  every 
effort  to  steer  the  wagon  around  a  corner.  He  saw  readily 


22  SELF-PROPELLED    VEHICLES. 

enough  that  to  attach  the  boiler  to  the  frame  of  the  carriage 
would  involve  the  difficulties  and  complications  incident  on  tele- 
scopic, or  extensile,  steam  connections  between  boiler  and  engine, 
which  would,  likely,  have  caused  serious  trouble.  He  adopted, 
therefore,  the  readiest  expedient.  His  wagon  worked  very  well 
on  a  straight  road,  but  developed  the  disagreeable  qualities  of 
"ending  up"  at  every  corner,  and  of  refusing  to  "obey  its  helm" 
whenever  a  stone  wall,  or  other  obstruction,  made  a  collision  con- 
venient. Had  he  slung  his  boiler  at  the  rear  of  the  forward  wheel, 
on  the  floor  of  the  wagon,  he  might  have  overcome  the  tendency 
to  "top-heaviness"  and  solved  the  problem  of  motor  road  traction 
a  century  sooner. 

Present  -  Day  Construction.  —  Practically  all  present-day 
motor  carnages  have  the  power  applied  to  the  rear  wheels,  doing 
the  steering  with  the  forward  pair.  This  plan,  of  course,  involves 
several  serious  problems,  the  foremost  of  which  is  as  to  how  a 
carriage  can  turn  a  corner,  long  or  short,  with  both  wheels 
moving  at  the  same  rate  of  speed.  If  anyone  will  observe  the  rear 
wheels  of  a  carriage  in  the  act  of  turning,  he  will  see  that  the  one, 
the  pivot  wheel,  does  not  revolve  or  revolves  yery  slowly,  as  the 
radius  of  the  described  arc  be  shorter  or  longer;  while  the 
other  wheel  carries  the  vehicle  around  with  it.  Now,  if  the 
power  is  to  be  applied  to  the  wheels,  either  by  chain  and  sprocket, 
by  spur  gears  or  by  a  crank,  either  one  of  six  devices  must  be 
adopted :  (i)  The  power  may  be  applied  equally  to  both  wheels, 
as  in  railway  locomotives,  in  which  case  only  turns  of  very  long 
radius  could  be  made.  This  is  the  reason  why  the  curves  of 
railroads  are  seldom  made  on  a  radius  of  less  than  three-eighths 
of  a  mile  (1,980  feet),  although,  since  the  steel  rails  offer  im- 
mensely less  resistance  to  the  wheels  than  an  ordinary  road  bed, 
often  allowing  the  drivers  to  revolve  without  progressing,  there 
is  much  smaller  need  of  devices  for  equalizing  or  compensating 
the  motions  of  the  pairs.  If,  then,  an  automobile  can  always  have 
a  ten-acre  lot  or  a  2OO-foot  road  to  turn  in,  it  may  be  able  to  drive 
on  the  locomotive  plan :  under  ordinary  conditions  it  must 
speedily  smash  something  and  come  to  grief.  (2)  The  motive 
power  may  be  applied  to  one  wheel  of  a  pair  and  not  to  the  other, 
either  or  both  turning  loose  on  the  axles.  But  such  a  plan  would 


HOW  A    MOTOR    CARRIAGE    TURNS. 


23 


not  only  give  the  carriage  a  constant  tendency  to  "lurch,"  render- 
ing forward  movement  exceedingly  difficult,  but  it  would  allow 
lurning  in  only  one  direction,  except  on  extremely  long  curves. 
(3)  There  may  be  two  separate  motors,  one  for  each  wheel,  both 
capable  of  being  controlled  with  the  steering  apparatus.  Such 
a  plan  has  been  put  into  actual  practice  by  several  manufacturers 
of  electrical  vehicles,  who  gear  their  motors  to  the  wheels,  or  use 
the  hub  to  support  either  the  armature  or  field  magnets,  as  the 
case  may  be.  One  maker  of  American  steam  carriages  has 
adopted  a  similar  construction,  connecting  several  small  cylinders 


FIG.  21.— Bergman's  Steam  Motor  Wheel.  A  number  of  steam  cylinders  are  arranged 
within  the  hollow  hub  of  the  wheel,  so  as  to  act  on  a  common  crank  on  the  axle.  The 
action  is  on  the  plan  of  a  compound  engine,  the  steam  being  exhausted  at  low 
pressure. 

direct  to  each  wheel  hub.  The  plan  has  its  advantages,  but  is  by 
no  means  as  simple,  accessible  and  sightly  as  using  one  motor 
with  sprocket  connections  to  the  centre  of  the  rear  driving  shaft. 
(4)  The  driving  wheels  may  be  attached  to  the  rotating  axle  by 
clutches,  which  may  be  "thrown  out"  by  geared  connections  to 
the  steering  mechanism.  To  be  really  practical  the  act  of  disen- 
gaging must  be  effected  by  the  steering  lever,  otherwise  the  driver 
might  forget  it  at  the  very  time  it  was  needed  most.  The  disad- 
vantage of  the  arrangement  is  thus  obvious;  for,  since  a  con- 
siderable motion  of  the  lever  is  required  to  release  the  clutch,  the 
device  would  be  of  use  only  on  short  curves,  as  in  turning  street 
corners,  when  the  lever  is  put  all  the  way  about.  On  long  curves 


24  SELF-PROPELLED    VEHICLES. 

there  could  be  no  certainty  that  disengagement  had  been  effected, 
unless  complex  devices  and  long  connections  were  employed, 
greatly  to  the  detriment  of  an  easy  operation  of  the  steering  lever. 
With  the  best  arranged  mechanism  there  must  be  some  stress 
and  strain  on  the  drive  wheels,  in  consequence  of  attempting 
by  hand  what  should  be  accomplished  automatically.  Also,  if  the 
clutch  is  to  be  thrown  out  every  time  the  steering  wheels  incline, 
ever  so  slightly,  the  driving  must  be  irregular,  and  the  speed  con- 
sequently impaired.  (5)  The  hub  of  each  wheel  may  be  provided 
with  a  ratchet  arrangement,  adapted  to  engage  the  axle  and  pre- 
vent it  from  rotating  forward  without  engaging  the  wheel.  Such 
a  construction  was  used  on  foot-propelled  tricycles  twenty  years 
ago,  but  was  then  found  faulty  because,  in  turning  corners,  the 
inner  wheel  had  to  do  the  driving.  Since  that  time  several  im- 
proved designs  have  been  made  that  allow  of  working  in  a  re- 
verse direction,  the  pawl  being  so  hung  as  to  shift  by  slight  fric- 
tion contact,  so  that,  if  the  axle  rotates  forward,  it  will  drive  the 
wheel  forward,  and  also  the  contrary.  With  all  produced  to  date, 
however,  the  same  fault  has  been  found :  When  attempting  a 
slight  hill,  there  is  no  way  of  controlling  the  vehicle  except  by 
applying  the  brake  until  the  power  is  reversed  and  the  pawls  can 
take  a  positive  grip.  Altogether,  the  best  pawl  and  ratchet  de- 
vices are  uncertain  and  unsatisfactory  in  action  and  also 
seem  unmechanical  and  unsuitable  for  motor  vehicle  use. 
(6)  The  construction  most  usually  adopted  is  to  attach 
both  drive-wheels  rigidly  to  a  revolving  axle  bar,  which 
is  divided  at  the  centre  to  connect  with  a  system  of  compensating 
or  balance  gear  wheels  enclosed  within  a  cylindrical  case 
carrying  the  sprocket.  Here  there  is  no  loss  of  power ;  no  need 
of  lowering  the  speed  on  curves  of  safe  radius,  and  no  necessity 
for  complicated  and  troublesome  devices  for  coupling  the  motive 
and  steering  functions. 

The  Requirements  in  Balance  Gears. — The  balance  or  com- 
pensating device,  as  used  on  motor  vehicles,  is  commonly  called 
a  "differential  gear/'  from  the  fact  that  the  primary  object  in- 
volved in  its  use  is,  as  we  have  seen,  to  allow  of  differentiation  or 
compensation  in  the  speeds  of  the  two  geared  wheels  and  their 
axles  in  making  curves.  Any  device  that  will  admit  of  a  steady 


HOW  A   MOTOR   CARRIAGE   TURNS.  25 

drive  in  straight-ahead  running,  a  difference  of  speed  in  the  two 
drive-wheels  in  turning  corners,  and  a  rapid  restoration  of  nor- 
mal conditions,  is  usable  for  this  purpose.  There  is,  however, 
another  necessary  function,  which  may  not  be  omitted — the  dif- 
ferential must  also  be  a  "balance  gear."  That  is  to  say,  it  must 
combine  with  the  function  of  compensation  an  even  or  balanced 
transmission  of  power  to  both  wheels.  Each  wheel,  so  long  as 
it  is  in  motion,  must  be  driven  with  the  same  degree  of  power. 


FIG.  22.— A  form  of  Differential  Gear  formerly  used  on  Tricycles.  The  studs  of  the 
pinions,  AA,  are  set  in  spokes  of  the  sprocket,  turning  on  their  own  axes  only  when 
either  of  the  wheels  of  the  vehicle,  attached  respectively  to  B  and  C,  cease  rotating, 
as  in  the  act  of  turning. 

At  no  time,  even  on  short  turns  when  one  wheel  is  stationary, 
acting  as  a  pivot,  is  it  permissible  that,  say  two-thirds  of  the 
power,  be  sent  to  one  drive-gear,  and  one-third  to  the  other. 
The  power,  transmitted  from  the  centre  of  the  divided  axle  shaft, 
must  always  be  the  same  in  both  directions,  even  though  one 
wheel  be  stationary.  On  some  driven  vehicles,  particuarly  two- 
track  foot-propelled  tricycles,  in  which  the  steering  wheel  is  set 
directly  ahead  of  one  of  the  drivers,  so  as  to  progress  on  the 


26  SELF-PROPELLED    VEHICLES. 

same  track,  it  is  desirable  to  use  a  compensating  gear  that  is  not 
a  balance  gear,  because  more  power  is  required  on  one  side  than 
on  the  other.  The  failure  to  understand  this  fact  in  the  early 
days  of  cycling  led  to  considerable  uncertainty  in  the  steering  of 
tricycles.  One  of  these  early  machines,  a  three-track  tricycle — 
one  having  the  steer  wheel  hung  forward  the  centre  of  the  two 
drivers— had  the  compensating  device  shown  in  an  accompanying 
figure,  instead  of  the  true  balance  gearing  it  should  have  had. 
The  device  shown  would  have  answered  excellently  well  in  a 
two-track  tricycle,  for  the  reasons  noted  above.  As  may  be  seen, 
the  device  consisted  of  a  large  internal  gear  wheel,  within  which 
and  rotating  about  the  same  axis  was  a  smaller  external  gear 
or  spur  wheel — the  two  meshing  with  the  spur  pinions  at  top  and 
bottom,  as  shown.  The  large  internal  gear  was  secured  to  the 
axle  of  one  wheel,  the  smaller  or  spur  wheel  to  the  opposite  one, 
and  power  was  applied  through  the  pinions  hung  on  the  sprocket. 
The  result  was  that  the  power-driven  pinion  transmitted  more 
power  to  the  internal  gear,  because  of  its.  greater  diameter,  than 
to  the  spur  gear,  thus  giving  one  wheel  a  tendency  to  revolve 
more  rapidly  than  the  other. 

Automobile  Gears. —  The  most  familiar  form  of  balance 
gears  for  compensating  the  drive  wheels  of  motor  carriages  is  the 
bevel,  or  miter,  gear  train.  This  is  the  original  form  of  the  device, 
and  was  used  on  steam  road  wagons  as  early  as  1843.  As  shown 
in  the  figure,  the  sprocket  or  spur  drive  wheel  has  secured  to  its 
inner  rim  several  studs  carrying  bevel  pinions,  which,  in  turn, 
engage  a  bevel  gear  wheel  on  either  side  of  the  sprocket.  These 
gear  wheels,  last  mentioned,  are  rigidly  attached  on  either  side  to 
the  inner  ends  of  the  centre  divided  axle-bar,  one  serving  to 
turn  the  left  wheel,  the  other,  the  right.  When,  now,  power  is 
applied  to  the  sprocket,  causing  the  vehicle  to  move  straight 
forward,  it  may  be  readily  understood  that  the  bevel  pinions, 
secured  to  the  sprocket,  instead  of  rotating,  which  would  mean  to 
turn  the  drive  wheels  in  opposite,  directions,  remain  motionless, 
acting  simply  as  a  kind  of  lock  or  clutch  to  secure  uniform  and 
continuous  rotation  of  both  wheels.  So  soon  as  a  movement  to 
turn  the  vehicle  is  made,  causing  the  wheels  to  move  with  differ- 
ent speeds,  a  fact  already  mentioned  in  connection  with  horse- 


HO W  A   MOTOR   CARRIAGE    TURNS. 


27 


drawn  carriages,  these  pinions  begin  to  rotate  on  their  own  axes, 
allowing  the  pivot  wheel  to  slow  up  or  remain  stationary,  as  con- 
ditions may  require,  while  still  continuing  to  urge  forward  the 
other  at  the  indicated  speed.  The  principle  involved  in  the  device 
may  be  readily  expressed  under  four  heads :  (i)  When  the  resist- 
ance offered  by  the  two  drive  wheels  and  attached  gear  is  the 
same  as  when  the  carriage  is  driven  forward,  the  pinions  cannot 
rotate.  (2)  When  the  resistance  is  greater  on  the  one  wheel  than 
on  the  other,  they  will  rotate  correspondingly,  although  still  mov- 


FIG.  23. 


FIG.  24. 


FIGS.  23  and  24.— Bevel  Gear  Differentials.  The  sprocket  gear  carries  three  bevel  pinions 
set  on  studs  on  three  of  its  radii.  These  pinions  mesh  with  bevel  wheels  on  either 
side,  which  wheels  are  attached  at  the  two  inner  ends  of  the  divided  axle  shaft.  The 
spur  drive  has  two  pinions  rotating  on  radii,  and  shows  the  action  to  better 
advantage. 

ing  forward  with  the  wheel  offering  the  lesser  resistance.  (3)  The 
pinions  may  rotate  independently  on  one  gear  wheel,  while  still 
acting  as  a  clutch  on  the  other,  sufficient  in  power  to  carry  it  for- 
ward. (4)  If  a  resistance  be  met  of  sufficient  power  to  stop  the 
rotation  of  both  wheels  and  their  axles,  the  condition  would  affect 
the  entire  mechanism,  and  the  pinions  would  still  remain  station- 
ary on  their  own  axes,  just  as  when  in  the  act  of  transmitting  an 
equal  movement  to  both  wheels. 

For  light  carriage  work  the  sprocket  or  spur  drive  generally 
carries  two  pinions,  as  shown  in  the  figure,  but  in  larger  vehicles 
the  number  is  increased  to  three,  four,  or  six,  and  the  size,  pitch 
and  number  of  the  teeth  varied,  according  to  requirements.  Of 
course,  it  is  essential  that  the  equalizing  gears  be  properly 


28 


SELF-PROPELLED    VEHICLES. 


chosen  for  the  work  they  are  to  perform,  in  the  matter  of  the 
number  of  the  pinions  and  of  their  teeth,  as  well  as  of  the  metal 
used,  since  the  great  strain  brought  to  bear  on  them  will  inevit- 
ably -cause  wear  and  strain.  With  even  the  best  made  bevel-gears 
there  is  a  danger  of  end  thrust  and  a  tendency  to  crowd  the 


Fio.  25.— Section  through  the  axis  of  a  bevel  gear  differential  train,  showing  two  bevel 
pinions  attached  at  top  and  bottom  of  the  sprocket  drum,  and  two  bevel  gear  wheels 
one  on  the  through  axle  shaft,  the  other  on  a  rotating  sleeve. 


pinions  against  the  collars,  with  consequently  excessive  wear  on 
both.  The  result  is  a  looseness  that  demands  constant  adjust- 
ment. 

Spur  Compensating  Gears  — In  order  to  avoid  the  difficul- 
ties encountered  with  bevel  gears,  spur-gears  were  invented,  and 
are  now  increasing  in  popularity.  In  this  variety  the  theory  of 


tiOW  A   MOTOR  CARRIAGE   TURNS,  2& 

compensation  is  the  same  as  with  bevel  gearing;  a  divided  axle, 
whose  two  inner  ends  carry  gear  wheels  cut  to  mesh  with  pinions 
attached  to  the  sprocket  pulley.  These  pinions  are,  however,  set 
in  geared  pairs,  with  their  axes  at  right  angles  to  the  radius  of 
the  sprocket,  which  is  to  say  parallel  to  its  axis.  As  will  be  seen 
in  the  accompanying  illustrations,  the  pinions  of  each  pair  are 
set  alternately  on  the  one  side  or  the  other  of  the  sprocket,  mesh- 
ing with  one  another  in  about  half  of  their  length,  the  remainder 
of  each  being  left  free  to  mesh  with  the  axle  spurs  on  the  one 


Fio.  26.— One  form  of  Spur  Differential  or  Balance  Gear.  The  two  inner  ends  of  the  di- 
vided axle  shaft  carry  spur  wheels,  which  mesh  each  with  one  of  every  pair  of  the 
the  three  pairs  of  open  pinions  shown.  As  these  pinions  mesh  together  both  rotate 
on  their  axes  as  soon  as  turning  of  the  wagon  begins. 

or  other  side.  Both  these  models  have  three  pairs  of  .pinions, 
one  of  each  meshing  with  either  of  the  axle  gears.  With  one  the 
ends  of  the  divided  axle  carry  internal  gears,  with  the  other 
true  spur-wheels.  The  operation  is  obvious.  When  the  vehicle 
is  turning,  one  rear  wheel  moves  less  rapidly,  causing  the  pinion 
with  which  it  is  geared  to  revolve  on  its  mate,  which,  in  turn, 
revolves  on  its  own  axis,  although  still  engaging  the  gear  of  the 
opposite  and  moving  wheel  of  the  vehicle.  The  motion  is  thus 
perfectly  compensated,  without  the  wear  and  thrust  inevitable 
with  bevels. 

A  Universal  Joint  Differential. — Another  differential  device, 
which  has  been  used  on  some  European  vehicles,  and  was 
formerly  patented  in  the  United  States,  is  shown  in  the  accom- 
panying figure.  In  this,  as  in  other  forms  of  differential  gearing, 


80  S&LF.PROPELL&& 

the  axle  shaft  is  divided  at  the  centre,  but  instead  of  rigidly  at- 
tached gears,  carries  a  universal  joint  on  each  inner  end,  on  which 
is  a  short  shaft  and  a  small  spur  pinion.  Over  the  divided  axle 
shaft  are  two  hollow  sleeves,  which  work  freely  over  it,  and  are 
connected  together  by  a  gear  box,  as  shown.  Within  this  gear 


Flo.  27.— Another  form  of  Spur  Balance  Gear.  The  action  is  the  same  as  in  Fig.  26,  ex- 
cept that  the  inner  ends  of  the  divided  axle  carry  internal  gear  wheels,  each  of  which 
meshes  with  one  pinion  of  each  pair. 

box  the  two  ends  of  the  wheel  axle  shafts  are  arranged  in  bear- 
ings at  an  angle  of  about  thirty  degrees,  so  that  the  pinions  can 
mesh.  The  driving  is  done  by  a  sprocket  attached  to  the  outer 
hollow  shaft  just  mentioned,  and  the  motion  is  transmitted  to  the 
inner  shafts  attached  to  the  vehicle  wheels  on  either  side  by  the 
differential  gearing;  the  spur  pinions,  in  this  as  in  the  former 
cases,  locking  fast  without  rotating  so  long  as  the  motion  of  the 
wheels  is  equal  and  the  carriage  is  driven  straight  ahead.  As 
soon  as  a  turn  is  made  the  pinions  begin  to  rotate  with  the 
compensating  effect  found  in  the  bevel  and  spur  gear  trains 
noticed  above. 

A  rather  simpler  variation  of  this  device  has  been  proposed, 
although  not  widely  used,  which  consists  of  two  gears  slightly 
beveled,  one  mounted  direct  on  the  straight  axle  shaft,  the  other, 


A  MOTOR  CARRIAGE  TUR&S,  fci 

on  a  universal  joint,  as  shown.  By  this  construction  one  univer- 
sal joint  is  saved,  while  the  compensating  action  of  the  device 
is  not  at  all  impaired. 

Disadvantages  of  a  Divided  Axle  Shaft.— The  practice  of 
dividing  the  axle  shaft,  thus  disconnecting  the  two  wheels  of 
the  vehicle,  is  a  source  of  weakness  which  was  recognized  and 
provided  against  long  since.  Although,  theoretically,  the  axle 
is  divided  at  the  centre,  as  we  have  described,  the  construction 
now  usually  adopted  is  to  mount  one  wheel  on  the  axle  shaft  and 
the  other  on  a  hollow  shaft  or  sleeve  which  works  over  it.  The 


FIG.  28. — A  Universal  Joint  Differential.  The  sprocket  or  spur  drive  turns  the  sleeve 
which  holds  the  gear  case  here  shown  in  section.  So  long  as  travel  is  straight  ahead 
neither  pinion  rotates  on  its  axis,  but  as  soon  as  a  turn  is  made  rotation  begins,  thus 
allowing  compensation  of  the  motion  of  the  two  wheels  of  the  wagon. 

solid  shaft  can  then  be  made  as  long  as  the  width  of  the  vehicle, 
the  differential  gear  wheel  belonging  to  it  being  secured  about 
midway  in  its  length.  The  other  or  hollow  shaft  is  about  half  as 
long,  so  that  its  gear  is  attached  at  the  end  and  is  immediately 
opposite  the  other,  both  meshing  with  the  pinions  attached  to  the 
sprocket.  Such  a  construction  involves  no  other  variation  from 
the  method  of  attaching  the  differential  gear-train  to  the  ends  of 
the  divided  axle  than  making  the  eyes  of  the  two  gear  wheels  of 
different  diameters,  so  as  to  fit  the  axle  shaft,  on  the  one  side, 
and,  the  hollow  axle,  or  sleeve,  on  the  other.  The  sprocket  is 
then  inserted  between  them,  being  held  in  position  by  the  mesh- 
ing of  the  axle  gears  with  the  pinions,  itself  turning  loose  on  the 
solid  through  shaft.  The  inner,  solid  axle  shaft  is  secured  in  posi- 
tion by  suitable  collars.  The  arrangement  may  be  understood 
by  reference  to  Fig.  25. 


82 

Another  Through  Axle  Shaft.— -Another  typical  method 
for  securing  the  strength  and  solidity  of  a  throiigh  axle  shaft  is  to 
attach  both  wheels  to  hollow  axles  of  the  same  diameter,  each  of 
which  carries  on  its  opposite,  or  inner,  end  the  gear  wheel  of  the 
differential  train.  Another  tube,  called  the  "liner  tube,"  of  the 
same  length  as  the  Width  of  the  vehicle,  is  then  inserted  in  the 
hollow  axles,  and  the  two  are  brought  together  so  as  to  bear  upon 
a  collar  secured  to  the  centre  of  the  liner  tube.  The  sprocket  and 


FIG.  29.— The  Hub- Enclosed  Differential  of  the  Riker  Carriages.  A  is  the  rotating  sleeve 
carrying  the  drive  spur.  It  is  bolted  to  the  yoke  carrier,  B,  and  the  flange  piece,  K, 
as  shown.  C  and  C  are  the  studs  of  the  bevel  pinions  attached  to  the  yoke  carrier, 
B.  F  is  the  bevel  gear  wheel  keyed  to  the  rotating  through  axle  shaft,  G,  whose  op- 
posite end  is  rigidly  attached  to  the  other  hub.  The  bevel  gear,  E,  is  keyed  to  the 
in-flanged  portion  of  the  hub,  D,  turning  on  the  reduced  portion,  H,  of  the  rotating 
axle  shaft. 

differential  pinion  train  are  inserted  and  held  in  place  in  a  fashion 
similar  to  that  used  in  the  previous  device,  the  inter-meshing  of 
the  bevels  serving  to  support  it. 

A  Hub-Enclosed    Differential The    problem    of    how    to 

secure  compensation  of  motion  between  the  two  rear  wheels,  and 
at  the  same  time  overcome  the  disadvantages  of  the  divided  axle 
shaft  is  solved  in  a  different  fashion  by  the  Riker  Electric  Vehicle 
Co.  Their  device  is,  briefly,  to  construct  the  wheels  with  box 
hubs  and  to  enclose  the  differential  gear-train  in  one  of  them. 
By  this  means  the  carriage  frame  enjoys  the  full  advantage  of  a 
solid  through  axle  shaft,  and  the  divided  connection  is  made  at 
one  end  instead  of  at  the  centre.  The  mechanism  is  as  follows : 
A  solid  through  axle  shaft  is  rigidly  attached  to  the  hub  of  one 
wheel,  and  has  the  opposite  one  running  loosely  upon  it,  secured 


ROW  A  MO  fOX  CARRIAGE 


by  nut  and  washer,  as  in  the  construction  used  for  horse-drawn 
vehicles ;  howbeit,  the  gearing  within  the  hub  prevents  its  ready 
removal  by  unscrewing  the  nut.  Over  the  solid  through  axle 
shaft,  which  rotates  with  the  wheel  attached  to  it,  is  sleeved  a 
hollow  rotating  shaft,  which  carries  the  drive  sprocket  or  spur. 
One  end  of  this  second  shaft  works  on  a  bearing  with  the  drive 
gear  wheel,  the  other  carries  a  hemispherical  yoke-carrier  to 
which  are  studded  differential  bevel  pinions  having  their  axes  on 
the  radii  of  the  shaft.  To  the  rear  of  this  yoke  piece  is  a  circular 


Fro.  30.— The  rear  axle  of  the  Thornycroft  steam  wagon,  showing  the  peculiar  arrange- 
ment of  the1  differential  gears  and  driving  connections.  The  driving  is  by  the  spur 
gear,  A,  attached  on  the  gear  box  in  the  usual  manner.  The  bevel  gear,  C,  is 
mounted  rigidly  on  the  right  side  of  the  solid  through-axle  shaft.  The  gear,  B,  is 
similarly  mounted  on  a  sleeve  at  the  left.  The  wheels,  X  and  Y,  turn  loose  on  the 
through  rotating  axle,  being  driven  by  the  springs,  D  and  E,  which  bear  upon  lugs 
at  the  rim,  as  will  be  subsequently  explained.  This  arrangement  permits  the  removal 
of  either  wheel,  as  in  horse  carriages.  G  and  F  are  the  wagon  springs,  one  resting 
above  the  rotating  axle,  the  other  above  the  rotating  sleeve. 

flange  piece  of  a  size  to  fit  the  inner  circumference  of  the  box  hub, 
and  turn  loosely,  when  the  differential  gearing  is  brought  into 
action:  when  the  drive  is  straight  ahead  it  turns  with  the  hub, 
being  of  one  piece  with  the  yoke  carrying  the  bevel  pinions.  The 
differential  train  is  completed  by  the  addition  of  the  two  side  gear 
wheels,  meshing  with  the  bevel  pinions,  as  in  other  systems  ot 
compensating  mechanism.  One  of  these  gear  wheels,  the  inner 


SELF-PROPSLLEb    VEHICL&S. 


one,  is  keyed  to  the  solid  through  axle  shaft,  and  turns  or  stops, 
according  to  the  motions  of  the  opposite  wheel  of  the  vehicle. 
The  other  is  keyed  to  an  in-flanged  sleeve  on  the  hub,  this  sleeve 
working  loose  on  the  extremity  of  the  solid  axle  shaft,  which  is 
turned  to  a  smaller  diameter  than  the  remainder  of  the  length, 
and  is  terminated  by  a  nut  and  washer,  as  previously  mentioned. 


\ 


Fio.  30a.— Plan  view  of  a  type  of  differential  and  transmission  gear  for  permitting  the 
use  of  dished  wheels.  H  is  the  driving  shaft,  which  drives  the  bevels,  B  and  C,  on 
the  two  half  axles,  D  and  E,  through  the  bevels,  A  and  F.  These  last  are  loose  on  H, 
being  held  rigid  by  intermeshinsr  with  pinions,  G,  G,  carried  on  a  cross  arm  on  H. 
Differential  action  between  the  two  rear  wheels  is  obtained  when,  in  turning,  B  or  C 
offers  resistance  to  the  rotation  of  A  or  F;  such  resistance  causing  the  pinions,  G  and 
G,  to  rotate  on  their  axes,  compensating  the  movements  of  the  two  wheels,  as  in 
other  differential  gears.  This  device  allows  the  use  of  dished  wheels,  since,  as  is 


maintained. 

The  differential  action  is  obvious,  since  the  bevel  pinions  are 
studded  to  a  yoke-carrier  at  the  end  of  the  hollow  drive-shaft,  in- 
stead of  to  the  sprocket  or  driving  spur ;  one  bevel-gear  of  the  train 
being  secured  to  the  axle  solid  with  the  wheel  opposite  to  the  dif- 
ferential hub,  and  the  other  to  the  body  of  the  differential  hub  itself. 


CHAPTER  FOUk. 


STEERING   A    MOTOR   CARRIAGE. 

Steering  Gear  of  Automobiles. —  In  a  horse-drawn  vehicle, 
as  we  have  seen,  the  front  axle  shaft  is  centre-pivoted  below  the 
body  of  the  carriage  and  in  turning  bears  on  the  "fifth  wheel." 
Such  an  arrangement  is  the  most  practical  for  this  class  of  vehicle, 
since  the  tractive  power,  the  horse,  can  pull  in  any  direction  with- 
out the  use  of  further  appliances  than  the  guiding  lines,  or  reins. 
In  motor  vehicles,  however,  it  is  not  always  practicable  to  so  com- 
bine the  steering  and  tractive  functions,  as  to  imitate  the  actions 


FIG.  31.— Panhard-Levassor  Light  Two- Passenger  Car,  having  a  Swinging  Front  Axle. 
The  steer  wheel  pillar  carries  an  arm  on  its  end  to  which  is  attached  a  link  bar  work- 
ing a  similar  arm  on  the  pivot  of  the  axle,  as  shown. 

of  a  horse.  Consequently,  it  is  necessary  to  provide  mechanical 
means  for  shifting  the  direction  of  the  forward  or  steering  wheels. 
This  result  may  be  accomplished  by  attaching  some  kind  of 
lever,  sprocket,  or  spur-gear  arrangement  to  a  "fifth  wheel,"  and 
operate  it  by  a  handle  near  the  seat  of  the  carriage.  To  success- 
fully accomplish  this  result  with  a  steering  handle,  such  as  is  used 
on  most  American  motor  carriages,  would  require  a  considerable 
expenditure  of  muscular  energy  and  a  wide  angle  of  leverage,  be- 
sides involving  delay  and  difficulty  on  many  turns.  With  a  well- 
geared  steering  wheel  it  has  been  successfully  adopted  by  Pan- 
hard  and  Levassor,  in  one  of  their  light  two-seated  cars.  For 
general  purposes,  however,  the  simplest  and  readiest  construction 

35 


8b  S&L&PROPELLED  VEHICLES. 

for  attaining  easy  steering,  and  at  the  same  time  securing  the* 
needed  stability  of  the  frame,  is  found  in  the  use  of  a  rigid 
through  axle  shaft  and  knuckle-jointed  stud  axles. 

Pivoted  Stud  Axles.— In  automobiles  the  forward  axle  shaft 
is  attached  beneath  the  body  of  the  vehicle,  so  as  to  admit  of  no 
rotary  movement  whatever  on  its  own  centre.  At  each  end  it 


FIG.  32.— The  Oakman-Hertel  Gasoline  Carriage,  showing  the  steer  wheels  set  in  and 
turned  by  bicycle  forks. 

carries  a  fork,  or  yoke,  to  which  is  pivot-bolted,  at  right  angles  to 
the  axle  shaft,  so  as  to  form  a  true  knuckle-joint,  a  boss  carrying 
two  branches,  one  of  them  of  cylindrical  shape  to  fit  the  axle  box 
of  the  wheel,  which  is  suitably  secured,  as  in  horse-drawn  vehicles, 
so  as  to  rotate  freely ;  the  other  being  an  arm,  shaped  for  attach- 
ing the  transverse  steering  link  bar.  This  link  bar  is  generally 
arranged  to  connect  the  steering  arms  of  both  stud  axles  on  the 
through  axle  shaft,  the  connections  for  the  control  handle  or 
wheel,  placed  conveniently  to  the  driver's  hand,  varying  with 
different  manufacturers.  Pivoted  axles,  which  are  generally 
known  as  the  Ackerman  axles,  and  were  invented  by  a  certain 
Lankensperger  of  Munich,  as  early  as  1819,  thus  furnish  the 
readiest  and  simplest  means  for  steering  motor  vehicles,  at  the 
same  time  permitting  maintenance  of  stability.  The  transverse 


STEERING  A    MOTOR   CARRIAGE.  37 

steering  link  bar  attached  to  an  arm  at  either  end  is  readily  ma- 
nipulated by  the  driver,  and  with  but  small  exertion,  since  the 
pivots,  attached  direct  to  the  axles  of  the  wheels,  permit  a  wide 
angle  of  variation  in  the  vehicle's  direction  of  travel  for  a  very 
slight  shifting  of  the  steering  handle.  The  balance  of  leverage 
being  also  in  the  driver's  favor,  it  is  possible  to  turn  the  vehicle  in 
any  desired  direction  quickly  and  with  ease.  This  same  fact  also 
involves  that  the  steering  handle  cannot  be  wobbled  or  vibrated. 


FIGS,  as  and  34.— Two  fortns  of  Stud  Steering  Axle,  showing  differing   arrangement  of 
steering  arms  and  pivots. 

The  Theory  of    Steering    Axles The  operation  of  pivoted 

steering  axles  depends  upon  fixing  the  pivot  as  near  as  possible 
to  the  centre  of  the  wheel,  in  order  to  enable  the  greatest  arc  of 
operation  for  the  smallest  motion  of  the  hand  lever.  In  this 
respect  the  steering  wheel  of  a  bicycle  is  typical,  and  some  makers 


38 


SELF-PROPELLED    VEHICLES. 


of  automobiles  who  use  steering  wheels  similarly  mounted  on 
forks,  either  in  pairs,  as  in  the  Oakman  gasoline  carnage,  or  as  a 
single  front  wheel,  as  in  the  Knox  three-wheel  gasoline  car- 
riage, are  able  thus  to  secure  a  remarkably  easy  and  efficient 
leverage.  But,  since  this  construction  is  not  the  most  suitable  for 
heavy  carriages,  and  is  not  generally  popular,  manufacturers  and 


FIG.  .35. — Inwardly  Inclined  Steering  Pivot  of  the  Duryea  Carriages.  The  lines  passing 
through  the  pivot  and  across  the  axle  converge  at  the  point  of  contact  of  the  tire 
with  the  ground,  thus  securing  the  effect  of  centre  steering. 

inventors  have  busied  themselves  devising  other  methods  for  ac- 
complishing the  same  result.  One  of  these  is  to  incline  the  stud 
axle  downward  at  such  an  angle  as  will  cause  the  tire,  or  periph- 
ery, of  the  wheel  to  strike  the  ground  at  a  point  coincident  with 
a  line  drawn  through  the  knuckle  pivot.  As  an  additional  ad- 


STEERING   A    MOTOR    CARRIAGE. 


39 


vantage  for  this  construction,  it  is  claimed  that  the  force  of  a 
collision  is  delivered  at  or  about  this  line  of  incidence,  rather 
than  on  the  hub  or  its  axle  connection,  thus  ensuring  greater 
security,  and  saving  the  driver  a  shock.  Another  device  is  to 
incline  the  pivot  axis  inward,  leaving  the  axle  horizontal,  or 
nearly  so,  with  the  result  that,  as  in  the  previous  case,  a  line 
drawn  through  the  pivot  strikes  the  ground  at  the  same  point 
with  the  periphery  of  the  wheel  which  is  itself  in  a  vertical  posi- 
tion. 


FIG.  36.— The  Haynes-Apperson  Double  Yoke  Steering  Pivot  Axle.  The  steering  arm  is 
attached  at  A,  thus  securing  the  turning  effect  at  approximately  the  centre  of  the 
wheel  hub. 

Constructional  Points  on  Steering  Axles. —  It  is  of  prime 
importance  that  the  construction  of  the  steering  knuckles  of 
pivoted  axles  should  be  as  heavy  and  durable  as  the  size  and 
weight  of  the  carriage  will  permit.  To  neglect  this  point  and 
attempt  a  lighter  and  prettier-looking  joint  will  involve  rapid 
wear  and  loose  bearings  to  the  detriment  of  good  steering  quali- 


40  SELF-PROPELLED    VEHICLES. 

ties.  At  this  point  it  may  be  in  place  to  remark  that  it  seems  to 
be  a  regular  superstition  with  some  manufacturers  of  motor  car- 
riages that  lightness  of  construction  is  the  first  thing  needful  in  a 
successful  vehicle.  For  this  reason  many  of  them  weaken  their 
carriages  by  using  tubular  frames  with  an  excessive  number  of 
joints,  thus  making  nearly  inevitable  a  rupture  somewhere  under 
stress  of  vibration  or  constant  use  on  rough  roads.  One  make 
of  American  gasoline  carriage,  which  combines  a  number  of  ex- 
ceptionally excellent  mechanical  conceptions,  carries  the  idea 
of  lightness  to  such  an  extreme  as  to  make  the  various  parts  far 
too  small  to  be  really  serviceable  under  test  conditions.  It  is 
probable  that  the  total  weight  thus  saved  would  not  equal  one- 


FIG.  37.— Form  of  Steering  Head  used  on  the  English  Daimler  Cars  and  Others.  The 
steering  arm  projects  from  the  front  of  the  pivot.  Part  of  the  drag  link  is  shown 
attached. 

third  of  a  hundred  pounds,  a  matter  of  no  particular  moment, 
when  we  consider  that,  as  it  is  claimed,  the  motor  is  of  ten  horse- 
power capacity.  Contrary  to  this  practice,  the  worth  of  a  motor 
carriage,  with  any  type  of  motor,  may  be  fairly  estimated  by 
considering  how  substantial  and  durable  are  the  parts  exposed  to 
running  stress — such  are  the  brake  drums,  the  differential  gear- 
ing and  the  steering  mechanism — and,  whether  such  parts  are 
of  sufficient  proportions  to  admit  of  easy  operation  and  the  resist- 
ance of  ordinary  violence.  These  qualities  are  particularly  essen- 
tial in  the  construction  of  the  pivoted  axles,  and  may  be  readily 
recognized  in  the  accompanying  figures  of  typical  structures. 

Other  Steering  Pivots. —  The  ends  of  superior  strength  and 
centre-steering  are  approximated  differently  by  other  carriage 


STEERING  A   MOTOR   CARRIAGE. 


41 


builders.  The  Haynes-Apperson  Co.  uses  a  double  yoke  ar- 
rangement ;  one  yoke  being  of  a  piece  with  the  through  axle 
shaft,  the  other  pivot-bolted  at  each  extremity  with  the  first,  and 
carrying  the  axle  spindle  at  its  centre.  The  National  Automo- 
bile and  Electric  Co.  have  a  vertical  bearing  at  the  end  of  the  axle 
shaft,  instead  of  the  usual  fork,  and  within  this  works  a  short  stud 

riL  E\^ 


El 


L«r 

FIG.  38  —Form  of  Steering  Pivot  and  Axle  used  by  the  National  Automobile  and  Electric 
Co.    The  steering  arm  is  attached  at  the  point  marked  A. 

piece  carrying  the  horizontal  spindle  at  the  base,  the  steering  arm 
being  bolted  at  the  top.  This  device  seems  to  be  a  simplified 
variation  of  the  one  used  on  the  Panhard  vehicles,  which  have  a 
similar  upright  bearing,  or  cone  pivot,  carrying  an  axle  stud  and 
axle  in  similar  fashion,  but  with  the  steering  gear  attached  at  the 
base. 

Pivoted  Wheel  Hubs— Several  manufacturers,  most  notably 
the  Riker  Electric  Vehicle  Co.,  have  attempted  to  improve  the 
operation  of  the  pivoted  steering  wheels  by  enclosing  the  pivot 
and  lever  arm  attachments  within  a  hollow  hub.  The  construc- 
tion includes  a  hollow  cylinder  or  tube  length,  which  is  pene- 


42  SELF-PROPELLED    VEHICLES. 

trated  by  the  end  of  the  axle  shaft  and  pivot-bolted  to  it,  so  as  to 
turn  in  either  direction  under  impulse  from  a  steering  handle 
fixed  to  its  inner  end  and  running  parallel  with  the  main  axle 
shaft.  Around  the  edges  of  this  pivoted  tube  run  two  hard  steel 
cones  which  engage  a  train  of  ball-bearings  enclosed  in  a  circular 
ball-race  or  retainer  fixed  on  the  inside  circumference  of  another 
and  larger  tube  or  box,  which  forms  the  hub  of  the  wheel,  and 
runs  freely  upon  the  first,  the  pivoted  box,  on  the  train  of  ball- 
bearings. This  device  bringing  the  pivot  exactly  at  the  centre 
of  the  wheel  is  an  eminently  effective  means  of  accomplishing 

I 


FIG.  39.— Pivoted  Steering  Hub  used  on  the  Riker  Carriages.    A  is  the  axle  shaft;  B,  the 
pivot  connecting  A  to  the  tubular  swinging  hub.  C.     E  and  E'  are  circular  cones 
which  bear  on  the  balls  mounted  in  the  ball  races,  " 
D  to  rotate  indei 
turns  both 


tecting  A  to  the  tubular  swinging  hub,  U.  &  and  E*  are  circular  cones 
r  on  the  balls  mounted  in  the  ball  races, 'F  and  F',  thus  permitting  the  hub 
3  independently  on  the  inner  tube,  C.  The  steering  arm,  H,  attached  to  C 
C  and  D  on  the  pivot,  B. 


easy  and  perfect  steering.  The  construction  must,  however,  be 
strong  and  comparatively  heavy,  so  as  not  to  achieve  ease  of 
operation  by  a  sacrifice  of  durability. 

Numerous  inventors  have  adopted  the  general  idea  of  placing 
the  pivot  within  the  hub,  and  effecting  the  steering  by  lever  and 
swivel  attachments,  but  the  Riker  hub  is  typical  of  most  such 
devices.  The  Clubbe  and  Southey  pivoted  hub  operates  on  a 
simpler  plan.  The  fork,  or  yoke,  on  the  through  axle  shaft  is 
slightly  bent  forward  at  the  end,  so  that  a  pivot  bolt-through  the 
eyes  pierces  a  boss  attached  tangent-wise  to  a  short  tubular  axle 
bearing,  in  which  the  stud  axle,  carrying  the  wheel,  revolves 
freely.  The  hub  is  hollow  and  hemispherical,  so  as  to  contain  the 
whole  mechanism  of  the  pivot  joint,  which  is  slightly  forward  of 


STEERING  A   MOTOR   CARRIAGE.  43 

the  centre,  giving  a  caster  action  to  the  wheel  in  turning.  The 
steering  arm  is  attached  to  the  axle  bearing  about  midway  in  its 
length  and  opposite  to  the  pivot  boss. 

Requirements  in  Steering  Motor  Carriages While  the  nov- 
ice in  mechanics  may  consider  that  some  of  the  details  and  con- 
trivances, thus  far  described,  are  quite  unnecessary,  he  will  read- 
ily recognize  their  importance  when  the  facts  are  explained. 
Thus,  when  informed  that  the  steering  wheels  of  an  automobile 
must,  in  turning  the  vehicle,  describe  concentric  arcs,  on  radii 
which  differ  in  length  by  the  distance  between  the  wheels,  he  will 
understand  that  the  axle  of  each  must  project  from  the  perch  at 
an  angle  diverse  from  that  made  by  the  other.  The  arcs  thus  de- 
scribed must  be  concentric  in  order  to  maintain  both  wheels  in 


FIG.  40.— The  Clubbe  and  Southey  Pivoted  Steering  Hub  used  on  the  Carriages  of  the 
Electric  Motive  Power  Co.,  of  England.  As  may  be  seen,  the  pivot  is  to  one  side  of 
the  axle,  thus  giving  the  wheel  a  true  caster  movement  in  turning. 

the  same  direction,  without  side-slip  or  resistance ;  they  must; 
be  on  radii  of  differing  length,  because,  as  is  obvious,  two  parallel 
wheels,  separated  by  even  a  minute  distance,  cannot  run  in  the 
same  tire  track.  The  wheel  axles  must  project  from  the  trans- 
verse axle-tree  at  different  angles,  because  the  two  wheels,  hav- 
ing the  same  diameter,  no  matter  how  their  relative  speeds  may 
differ,  will  by  any  other  arrangement  fail  to  run  in  the  same 
curved  direction.  This  principle  is  not  applied  in  the  steering  of 
horse-drawn  carriages  for  several  reasons:  (i)  The  wheels,  being 
cairied  at  either  end  of  a  centre-pivoted  swinging  axle-tree,  are 
always  held  on  the  radius  of  the  turning  arc.  (2)  The  steel  tires 


44  SELF-PROPELLED    VEHICLES. 

permit  considerable  slipping,  impossible  with  rubber,  thus  al- 
lowing a  moderately  complete  compensation  of  diverse  arcs  and 
speeds.  (3)  The  motive  power  being  derived  from  an  outside 
agent — the  horse — the  continuous  movement  is  not  impaired,  or 
the  steering  rendered  uncertain,  as  must  be  the  case  in  a  self- 
propelling  vehicle,  which  is  moved  from  the  rear.  (4)  As  the 
careful  driver  very  soon  learns,  the  arc  of  turning  must  be  on  a 
radius  of  generally  twice  the  carriage  length,  if  an  upset  is  to  be 
avoided,  although  this  depends  on  the  speed  and  location  of  the 
centre  of  gravity. 

The  same  principle  is  applied  in  railroad  cars  and  locomotives 
in  a  manner  impracticable  for  either  horse  or  motor  carriages. 
Here,  although  the  wheels  are  always  rigidly  attached  in  pairs  at 
either  extremity  of  rotating  through  axles,  and  in  fours  to  the 


Fio.  41.— The  Loomis  Steering  Head.  This  device  differs  from  the  conventional  yoke  and 
pivot  arrangement  in  the  fact  that  the  yoke  is  on  the  stud  axle  instead  of  the  axle- 
tree  end,  and  is  offset  from  the  end  centre,  thus  allowing  of  a  caster  movement. 

trucks,  composed  of  two  parallel  through  rotating  axles  with 
their  attached  wheels,  the  differing  concentric  arcs  described  by 
the  two  rails  of  the  track  in  rounding  a  curve  are  followed. 

Constructional  Theory   of   Railroad  Wheels. — As    may    be 

readily  understood,  the  theoretical  requirements  to  enable  the 
wheels  on  the  axles  of  a  railroad  car  to  perfectly  follow  both  rails 
of  a  curved  track  involves  that  they  be  constructed  to  form  a 
cone,  whose  apex  is  at  the  centre  of  the  described  arc  and  whose 
base  is  the  outside  face  of  the  outer  wheel.  In  other  words,  the 
wheel  nearest  the  centre  of  the  curve  would  have  to  be  made 
of  smaller  diameter  than  the  other,  which,  although  the  theoreti- 


STEERMG  A   MOTOR  CARRIAGE. 


45 


cally  perfect  construction  for  curves,  would  render  the  car  useless 
for  straight-ahead  travel,  if  practically  carried  out.  To  accom- 
plish the  desired  end,  however,  car  wheels  have  been  made  with 
a  cone-shaped  tread — forming,  in  fact,  a  double  cone — the  base 
of  the  cone  being  against  the  flange  of  the  wheel.  In  turning  a 
curve,  then,  the  outer  wheel,  impelled  by  centrifugal  force,  rotates 


_. 

^  —  ^~.-" 

i 
i 

x"     _     1 

K-  tf-» 

1 

1 

V^ 

N  ^ 

\3 

FIG.  42.—  The  Coned 

*     -*j*~-« 

1                       -^ 

1 
1 

1 

_i  P 

^ 

^ 

<4 

i 
i 
l 

=^rrrr^._ 

to  allow  the  two  wheels  to 

Tread  of  a  Railroad  Car  Wheel,  intended 

describe  concentric  arcs  in  turning  curves. 


FIG.  43.— Position  of  the  Wheels  of  a  Railroad  Car  on  the  Rails  in  Turning  a  Curve. 

on  its  largest  diameter,  while  the  inner  wheel,  from  the  same 
cause,  rotates  on  its  smallest.  Thus  is  approximated  the  require- 
ment that  the  two  wheels  on  an  axle  should  run  on  different 
diameters  in  making  a  curve.  In  practice  the  stress  and  friction 
of  travel  eventually  wears  down  the  coned  surface,  particularly 
at  the  flange  of  both  wheels,  where  it  is  most  needed,  leaving  con- 
siderable of  the  compensating  effect  on  curves  to  the  slipping 
of  the  wheels  on  the  rails,  or  to  the  angular  difference  due  to  ele- 
vating the  longer,  or  outer,  rail  of  the  track. 


46  SELF-PROPELLED    VEHICLES. 

Angles  of  the  Steering  Axles. — With  an  understanding  of 
the  positive  necessity  of  providing  some  means  to  keep  both  the 
steering  axles  of  a  motor  carriage  on  radii  from  a  common  centre, 
in  order  to  neutralize  the  tendency  to  side  slip  and  skidding,  and 
secure  positive  control  of  the  vehicle's  direction',  it  is  evident  that 
some  arrangement  must  be  included  for  varying  the  angles  of 


Fio.  44.— Diagram  Illustrating  the  Position  of  the  Steering  Wheels  in  Turning.  As  will 
be  seen,  they  both  are  tangential  to  arcs  described  on  a  common  centre,  as  is  neces- 
sary in  order  to  describe  such  concentric  arcs  and  give  positive  steering,  when  the 
motive  impulse  is  from  behind. 

the  two  from  the  transverse  axle  bar.  As  may  be  readily  under- 
stood, when  a  carriage's  travel  is  changed  from  the  straight- 
ahead  direction  to  a  curve,  the  steering  wheel  moving  on  the 
in-track,  or  smaller  arc,  must  assume  a  greater  angle  at  the  axle 
than  the  outer  wheel,  which  moves  on  the  larger  of  the  two  con- 
centric arcs.  It  is  further  evident  that  such  variation  of  axial 
angles  must  be  accomplished  by  some  device  at  the  steering  arms 
of  the  stud  axles.  If  these  steering  arms  be  fixed  at 
right  angles  to  the  axles,  so  that  the  transverse  drag- 


STEERING  A  MOTOR  CARRIAGE. 


4? 


link  is  of  a  length  about  identical  with  the  distance  between  the 
wheel  bases,  any  effort  to  turn  the  wheels  in  steering  will  shift 
the  angles  of  both  arms  with  the  fixed  axle-tree  equally,  hence, 
causing  the  axles  to  assume  positions  as  radii  from  different  cen- 
tres. The  result  will  be  that  the  outer  wheel  will  describe  an  arc 
tending  to  cross  those  described  by  all  the  other  wheels,  and 
may  slide  or  rub,  without  revolving,  as  much  as  one  foot  in  every 


101 


121 


Fia.  45. 


I2J 


Fio.  46. 


FIG.  47. 


Fias.  45,  46  and  47. — Diagrams  of  Motor  Carriage  Forward  Axles,  showing  three  arrange- 
ments of  link  bars  and  steering  arms.  In  the  first  the  steering  arms  are  inclined  in- 
ward at  the  required  angle  and  connected  across  the  carriage  width  by  a  single  link. 
In  the  second  the  steering  arms  are  fixed  at  right  angles  to  the  axle-tree,  and  the 
angle  of  inclination  is  made  at  a  centre  pivoted  bell  crank.  In  the  third  the  angle  of 
inclination  is  divided  between  the  steering  arms  and  the  central  bell  crank.  Theo- 
retically, the  sum  of  the  angles  in  the  third  figure  is  equal  to  that  in  the  first,  and  to 
the  angle  of  the  bell  crank  in  the  second. 

six.  Such  a  procedure  must,  of  course,  retard  the  progress  of  the 
vehicle  very  seriously,  and,  from  the  uncertainty  of  steering  in- 
volved, must  be  particularly  troublesome,  even  dangerous,  on 
narrow  turns.  It  is  evident  in  this  case  that  the  outer  wheel 
axle  is  at  too  great  an  angle,  or  that  the  inner  is  at  too  small  an 
angle.  The  simplest  method  of  at  once  obviating  this  trouble 
and  also  securing  the  proper  angles  of  the  axles  is  to  incline  the 
two  steering  arms  inward  from  the  right  angle  and  make  the 
transverse  drag-link  shorter  than  the  distance  between  the  axle 


48 


pivots.     If  the  drag-link  be  forward  the  axle-tree,  the  steering 
arms  are  inclined  outward. 

With  this  arrangement,  as  may  be  readily  understood,  any 
effort  to  change  the  direction  of  the  travel  will  cause  the  arm  of 
the  outer  wheel  to  approach  the  right  angle  with  the  transverse 
through  axle  bar,  and  cause  the  arm  of  the  inner  wheel  to  move 
proportionately  away  from  the  right  angle.  Moreover,  since  the 
end  of  the  transverse  drag-link  attached  to  this  inner  axle-arm 
must,  in  the  act  of  thus  widening  the  angle,  be  approached  nearer 
and  nearer  to  the  immovable  through  axle  bar,  it  must  describe 


FIG.  48.— Steering  Connections  of  the  Panhard  Carriages.  The  spindle  of  the  steering 
hand  wheel  carries  a  worm  gear  at  its  base,  which  actuates  a  toothed  sector,  as 
shown.  This  swings  an  arm  and  moves  the  drag-link  attached  to  the  arm  at  the  base 
of  the  steering  head.  The  transverse  drag-link  connecting  the  two  steering  heads 
is  attached  to  the  arm  extending  from  the  front  of  the  carriage.  The  link  between 
the  steering  head  and  the  sector  arm  has  ball  joints  and  can  adjust  the  distance  as 
the  carriage  rises  and  falls  on  the  springs. 

an  arc,  thus  passing  through  a  greater  number  of  degrees  than 
will  the  opposite,  or  outer,  end.  Consequently,  the  object  of  se- 
curing a  greater  angular  inclination  for  the  axle  of  the  inner  wheel 
will  be  accomplished  and  the  proper  difference  for  all  usual  con- 
ditions between  the  angles  of  the  two,  approximated.  That  is, 
although  it  generally  happens  that  the  angular  inclination  of  the 
steering  arms  works  best  on  curves  of  radius  midway  between 
the  extremely  long  and  extremely  short,  it  has  been  found  that 


A   MOTOR   CARRIAGE  49 

the  difference  is  not  sufficiently  great  to  disturb  the  parallelism 
the  described  arcs  or  cause  damaging  slips  and  skidding. 


FIG.  50. 

FIGS.  49  and  50.  —The  Steering  Arrangement  of  the  Gobron-Brillie  Carriages.  In  both 
figures  A  is  a  hand  wheel,  at  the  end  of  whose  spindle,  D,  is  an  arm,  E,  to  which  is 
pivoted  a  toothed  sector,  B.  The  arm,  E,  being  moved  as  the  wheel,  A,  is  turned, 
carries  around  with  it  the  pivot  of  the  sector,  B.  This  sector  meshes  with  the  pinion, 
C,  turning  loose  on  the  steering  pillar,  as  shown,  and  is  accordingly  rotated  through 
an  arc.  Thus  the  arm,  F,  attached  to  the  pivot  of  B,  on  E.  has  a  double  motion, 
which  involves  that  the  slightest  movement  of  the  wheel.  A,  is  unusually  effective  in 
actuating  the  steering  arms,  through  the  link  attached,  as  indicated,  to  the  end  of  F. 
Also,  any  stress  at  the  wheels  is  unable  to  reverse  or  disturb  the  movement  thus 
directed.  The  spring,  G,  attached  to  the  arm,  H,  serves  to  steady  the  movement  and 
restore  F  to  normal  position  when  required. 


56  SELF-PROPELLED    VEHICLES, 

Arrangement  of  the  Steering  Handle. — The  steering  arms 
on  the  pivoted  axle  bosses  are  connected  across  the  width  of  the 
carriage  by  a  drag-link  bar,  which  transmits  the  impulses  given 
at  the  wheel  or  lever  by  the  driver's  hand.  Most  often  the  at- 
tachment is  made  by  a  second  link  bar,  attached  at  one  end  to 
one  of  the  steering  arms,  and,  at  the  other,  to  the  steering  wheel 
or  lever,  so  that  this  particular  arm  is  dragged  or  pushed,  ac- 
cording to  the  desired  direction  in  steering.  The  majority  of 
American  motor  carriages  are  equipped  with  a  handle  and  lever 
— sometimes  in  the  centre  of  the  vehicle,  sometimes  at  the  side — 
while,  in  Europe,  the  hand  wheel  is  the  most  typical  arrangement. 
The  accompanying  diagrams  show  several  typical  methods  of 
arranging  the  steering  mechanism  with  reference  to  the  steering 
link.  One  of  the  most  common  devices  is  that  used  in  vehicles 
of  the  De  Dion  voiturette  type,  described  as  the  "ordinary  bicycle 
steering."  The  handle  bar  and  post  may  be  vertical  or  inclined, 
and  is  connected  with  the  steering  device  in  front  by  link  rods, 
gears  or  chains.  On  some  of  the  Panhard  vehicles  the  link  bar 
actuating  the  steering  arm  is  jointed  to  a  toothed  sector  which 
engages  a  worm  thread  on  the  end  of  the  rearwardly-inclined 
shaft  of  the  hand  wheel  before  the  driver's  seat. 

As  regards  lever  steering  and  wheel  steering  it  is  mostly  a 
matter  of  design.  The  first  objection  to  the  lever  that  occurs 
to  the  mind  of  a  novice  is  that,  if  attached  to  a  vertical  steering 
head  and  of  sufficient  length  to  be  convenient  to  the  driver's 
hand,  a  larger  arc  will  be  described  than  is  perfectly  comfortable. 

On  this  account,  however,  most  lever  steerings,  operate  not  di- 
rectly on  the  steering  head,  but  through  intermediate  levers  by 
which  the  power  may  be  varied  to  suit  the  requirements  of  each 
turn.  Generally  speaking,  a  short  steering  lever  turned  at  a 
considerable  angle  to  produce  the  required  deflection  of  the 
steering  gear  is  preferable,  although,  in  reality,  it  becomes  a  re- 
duced and  modified  form  of  steering  wheel.  By  lessening  the 
load  on  the  front  of  the  carriage,  by  properly  inclining  the  steer- 
ing heads,  and  by  providing  to  avoid  all  lost  motion,  the  steering 
effort  may  be  so  reduced  as  to  make  possible  the  use  of  a  short 
lever,  such  as  is  used  on  the  Duryea  and  De  Dion  vehicles,  with 
the  accompanying  advantages  of  easy,  ready  handling  and  small 
arcs. 


STEERING  A  MOTOR  CAKRtAGE. 


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52  SELF-PROPELLED    VEHICLES. 

Practical  Points  on  Steering  Angles — In  general,  the  steer- 
ing angle  of  an  automobile  carriage,  which  is  to  say  the  sum  of 
the  inclinations  of  the  two  steering  arms  from  the  right  angle,  is 
between  fifty  and  sixty  degrees,  giving  an  inclination  for  each 
arm  of  between  twenty-five  and  thirty  degrees.  Some  of  the  best 
makes  of  carriage  have  it  at  or  about  twenty-five  degrees.  As 
shown  in  the  accompanying  diagrams,  however,  various  de- 
signers have  modified  the  typical  arrangement  of  inclining  the 
steering  arms  inward  and  using  a  short  drag-link  to  connect 
them.  Some  have  adopted  the  device  of  placing  the  arms  at  right 
angles  and  using  a  link  in  two  sections  connected  to  a  fork  or 


FIG.  52.-Steering  Arrangement  of  the  Clarkson-Capel  Steam  Wagon.  The  spindle  of  the 
steering  wheel  carries  a  screw  at  its  end,  which  works  a  boss,  as  the  wheel  is  turned, 
thus  actuating  the  lever  and  drag-link  attached  to  the  arm  of  one  of  the  axle  pivots. 

bell  crank  having  the  total  required  angle,  fifty  or  sixty  degrees, 
and  pivoted  at  the  centre  of  the  fixed  axle  bar.  Others  have  so 
combined  this  with  the  first-named  construction  as  to  divide  the 
angle  between  the  centre-pivoted  bell  crank  and  the  steering 
arms,  making  the  former,  say  thirty  degrees  and  the  two  latter 
fifteen  degrees  each.  The  primary  object  achieved  in  either  of 
these  devices,  as  compared  with  those  previously  named,  is  tp 


STEERING   A    MOTOR   CARRIAGE. 


53 


ensure  the  end  of  ready  manipulation  of  the  steering  lever.  The 
first-named  construction  is  the  one  best  suited  to  carriages  hav- 
ing the  steering  pivot  in  the  theoretically  correct  place — within 
the  hub.  When  for  structural  reasons  the  transverse  drag-link 
bar  is  placed  in  front  of  the  axle-tree,  a  position  preferred  by  sev- 
eral manufacturers,  the  steering  arms  attached  to  the  bosses  of 
the  swinging  axles  are  inclined  outward,  instead  of  inward,  at 
the  angles  found  most  suitable  with  reference  to  the  width  of  the 
vehicle  between  the  wheel  pivots  and  to  the  diameter'  of  the 
wheels.  A  very  useful  construction,  used  on  the  Duryea  car- 
riages and  others,  is  to  incline  the  upper  end  of  the  axle  boss, 
or  pivot,  inward  toward  the  centre  of  the  vehicle,  so  that  a  line 
drawn  through  the  axis  touches  the  ground  at  the  centre  of  the 
pneumatic  tire.  This  achieves  not  only  the  desirable  end  of  cen- 
tre-steering, as  already  mentioned  above,  but  also  allows  a  cer- 
tain inclination,  or  rake  to  the  steering  wheels,  as  in  a  bicycle, 
when  making  a  turn.  The  rake  is  a  positive  advantage  to  ready 
steering  qualities,  when  the  inclination  of  the  axle  pivot  is  not  at 
so  great  an  angle  as  to  bring  unusual  side  strain  on  the  wheels. 
Other  things  being  equally  favorable,  it  is  also  efficient  in  re- 
ducing the  steering  effort. 


FIG.  53.-8teering  Arrangement  of  the  Amadie  Bolee  Steam  Coach  (1881).  A  hand  wheel 
spindle  carries  a  spur  pinion  at  its  base,  which  working  on  an  internal  geared  sector, 
as  shown,  operates  the  hell  crank,  actuating  the  two  transverse  drag-links. 


CHAPTER  FIVE. 


VARIOUS      DEVICES      FOR     COMBINING     THE     STEERING     AND 
DRIVING    FUNCTIONS. 

Front  Driving  and  Steering.—  It  will  require  very  little  re- 
flection to  understand  that  to  drive  direct  on  a  pivoted  steering 
wheel  must  involve  a  peculiar  and  carefully  adjusted  gearing,  so 
that  the  two  functions,  driving  and  steering,  may  be  exercised 
without  interference.  Were  it  possible  always  to  apply  the  power 
to  the  forward  wheels  it  would  be  advantageous  in  a  number  of 
particulars.  Since,  however,  its  accomplishment  demands  the 
use  of  crown  or  bevel  gears,  with  a  consequent  strength  and 
weight  of  construction,  it  is  not  perfectly  practicable  in  the  lighter 
patterns  of  motor  carriages.  The  accompanying  figure  of  a  com- 
bined driving  and  steering  device,  as  used  in  some  of  the  Hurtu 
electric  cabs,  shows  one  arrangement  of  gearing  for  accomplish- 
ing the  result.  Here  /  is  the  armature  of  the  motor,  NN,  the 
magnets  and  B,  a  frame  supporting  the  armature  spindle  which 
rotates  on  the  axis,  XX.  To  this  spindle  is  attached  the  spur 
pinion,  P,  which  meshes  with  the  pinion,  r,  turning  on  the  axis, 
yy,  within  the  boss  of  the  steering  pivot.  The  spur  pinion,  r,  is 
made  in  one  piece  with  the  bevel  pinion,  a,  and  this  latter  engages 
the  toothed  bevel  ring,  b,  which  is  clamped  to  the  spokes  of  the 
wheel,  RR.  As  may  be  understood,  it  is  possible  to  swing  the 
wheel,  RR,  on  the  axis,  yy,  fixed  in  the  yoke,  E,  without  inter- 
fering with  the  transmission  of  driving  power  from  the  pinion,  a, 
to  the  bevel  ring,  b,  thus  permitting  the  vehicle  to  be  steered  and 
driven  on  the  same  wheel. 

A  more  recently  patented  device  of  the  same  description  for 
electric  wagons  uses  a  separate  axle  for  each  steering  driver,  on 
which  is  mounted  a  separate  motor.  The  power  is  transmitted 
by  a  spur  pinion  engaging  an  internally-geared  ring  secured  to 
the  spokes  of  the  wheel,  and  the  whole  device,  axle,  motor  and 
wheel,  being  pivoted  to  the  end  of  a  rigid  transverse  bar,  may  be 
turned  by  the  steering  gear.  The  steering  pivots  are  operated  by 

54 


COMBINED   STEERING   AND   DRIVING. 


55 


a  worm  gear  at  the  top  of  each  being  engaged  by  a  worm  pinion  at 
the  extremity  of  a  transverse  rotatable  bar.  In  either  of  these 
devices  the  act  of  steering  may  be  accomplished  without  moving 
the  motor  armature. 


FIG.  54.  FIG.  55. 

FIG.  54.— Motor  Steering  Wheel  of  the  Hurtu  Cabs.  A  drag-link  attached  to  the  arm  of 
the  pivots  can  turn  the  wheels  without  disturbing  the  operation  of  the  motor. 

FIG.  55.— Steering  Motor  Wheel  Arrangement,  by  which  a  worm  gear  and  pinion  device, 
actuated  as  shown  by  bevel  gears,  turns  the  stud  axle  entirely  around  with  the  at- 
tached motor  and  gearing,  without  interrupting  a  steady  drive. 

All-Wheel  Driving — Numerous  devices  have  been  introduced 
for  the  purpose  of  driving  on  all  four  wheels  of  a  motor  carriage. 
Most  such  are  objectionable,  however,  on  the  ground  of  greatly 
complicating  the  mechanism  and  thus  proving  nearly  impracti- 
cable for  lighter  kinds  of  vehicles.  The  accompanying  figure 
shows  one  of  the  best  of  these,  the  subject  of  a  recently  granted 
patent.  As  may  be  seen,  the  driving  is  by  two  shafts  and  two- 
sleeves  running  in  the  length  of  the  carriage,  and  transmitting  the 
rotative  movement  from  two  separate  trains  of  bevel  gears  to  the 
front  and  rear  wheels  by  sets  of  universal  joints.  The  front 
wheels  rotate  in  pivoted  bearings,  so' as  to  be  effectually  turned 


56  SELF-PROPELLED    VEHICLES. 

in  steering,  without  interfering  with  their  motion  on  their  own 
axes,  or  in  any  way  altering  the  action  of  the  motor.  As  may  be 
readily  understood,  a  proper  arrangement  of  bevel  gearing  at  the 
pinions  attached  to  the  rotating  shafts  and  sleeves  will  give  the 
effect  of  compensating  the  speeds  of  the  two  rear  wheels  in  turn- 
ing, according  to  the  principles  previously  explained. 


FIG.  66.— Recently  Patented  Device  for  Driving  on  all  Four  Wheels  by  a  System  of  Uni- 
versal joints.  The  steering  arms  are  not  inclined,  since  the  wheels  being  driven  fol- 
low their  paths  without  slipping. 

All- Wheel  Driving  and  Steering.—  The  advantages  to  be 
gained  in  a  practical  device  for  applying  power  to  all  the  wheels 
are  still  further  enhanced  by  the  additional  feature  of  steering 
with  all  four.  This  is  desirable,  if  we  wish  such  advantages  as 
come  by  driving  on  the  front  wheels  and  steering  with  the 
rear.  To  steer  with  the  rear  wheels  only  is  not  always  prac- 
ticable. When  the  front  wheels  only  are  driving  it  is  impos- 
sible to  propel  the  carriage  up  a  steep  hill,  owing  to  the  shift- 
ing centre  of  gravity.  With  the  Cotta  steam  carriage  the  power 
is  divided  by  a  quadruple  compensating  gear  into  four  equal  and 
independent  parts,  and  is  then  transmitted  to  each  of  the  four 
wheels,  which  are  30  inches  diameter  with  2^-inch  tires.  By 
this  arrangement  the  wheels,  each  being  independent  of  the 
others,  are  allowed  freedom  in  speed  in  passing  over  obstructions 
or  unevenness  in  the  roadway  without  reference  to  the  travel  of 


COMBINED   STEERING  AND   DRIVING. 


57 


FlG.  57.— Cotta  Carriage  Frame  for  Four-wheel  Driving  and  Steering.  The  motor  drives 
on  a  balance  gear  at  the  centre  of  the  frame,  whence  motion  is  transmitted  to  all 
wheels  by  chain  and  sprocket  connections.  All  four  hubs  are  pivoted  for  steering, 
and  are  connected  in  pairs  across  the  width  of  the  frame  by  drag-links.  The  two 
links  are  geared  together,  as  shown,  so  that  the  travel  of  all  the  wheels  may  be  varied 
at  once  by  the  steering  lever. 


58  SELF-PROPELLED    VEHICLES. 

any  of  the  others,  and  under  all  conditions  each  wheel  receives 
one-fourth  of  the  power,  and  does  its  share  of  the  propelling  of 
the  vehicle.  It  is  plain  to  see  the  necessity  of  such  a  compensat- 
ing device,  when  we  consider  that,  on  a  perfectly  smooth  road- 
way and  traveling  straight  ahead,  each  wheel  would  make  a 
different  number  of  revolutions  in  a  given  distance,  owing  to  the 
fact  that  it  is  impossible  to  have  tires  inflated  exactly  alike,  and 


FIG.  58.— The  Pretot  Fore-Carriage  shown  attached  to  a  Victoria  Carriage.  The  attach- 
ment is  on  a  fifth  wheel  running  on  roller  bearings,  and  turning  by  geared  connec- 
tions with  the  steering  hand  wheel. 

also  that  some  wheels  will  carry  more  weight  than  others,  de- 
pressing some  tires  more  than  others  and  giving  them  a  dimin- 
ished radius  and  less  circumference. 

"The  Cotta  steering  pivot  is  in  the  direct  centre  of  the  wheels, 
the  wheels  only  oscillating  in  turning  a  curve,  doing  away  with 
all  side  jar  on  the  steering  lever  on  rough  roads,  so  objectionable 
in  other  vehicles.  As  this  vehicle  is  intended  to  be  a  success  on 
bad  roads  as  well  as  good  ones,  the  makers  have  arranged  to 
guide  all  four  wheels,  bringing  the  rear  wheels  around  in  the 
same  track  as  the  front  ones  in  rounding  a  curve,  and  making 
but  two  tracks,  instead  of  four,  when  in  the  mud,  making  it  as 
easy  to  travel  on  a  curve  as  straight  ahead." 

As  to  Rear  Steering. —  In  considering  some  of  the  advantages 
to  be  derived  from  front  driving  arrangements,  the  idea  of  steer- 
ing with  the  rear  wheels  only  mi^ht  seem  equally  advantageous 
to  some  minds.  But  this  is  imnracticable  for  motor  carriages, 
since  its  adoption  would  mean  the  destruction  of  good  steering1 


COMBINED   STEERING  AND   DRIVING.  59 

qualities.  The  situation  is  well  expressed  in  the  "Horseless 
Age" :  ''The  objections  to  rear  steering  are  that,  when  a  car- 
riage is  standing  near  a  curb,  it  is  impossible  to  turn  off  sharply, 
as  the  steering  wheel  (rear)  would  run  into  the  curb;  and  that, 
when  near  a  ditch  or  impassable  section  of  the  road,  in  order  to 
turn  away  from  these,  the  steering  wheels  (rear)  must  first  run 
toward  them,  which  may  lead  to  difficulties." 

Automobile  Fore-Carriages  and  flotor  Wheels.—  Among 
other  solutions  of  the  important  problem,  as  some  consider  it,  of 
combined  driving  and  steering  on  the  front  wheels,  may  be  men- 
tioned such  devices  as  the  Pretot  fore-carriage,  manufactured  in 
France  and  England,  and  also  introduced  in  the  United  States. 
As  shown  by  the  accompanying  figure,  this  device  is  a  two- 
wheeled  truck,  which  may  be  attached  to  almost  any  vehicle  by 
slight  alteration,  and  capable  of  being  turned  for  steering  on  a 
kind  of  fifth  wheel  arrangement  running  on  rollers.  The  fore- 
carriage  itself  contains  a  gasoline  motor  of  between  five  and  ten 
horse-power,  with  suitable  transmission  gear,  permitting  three 
speeds  forward  and  a  reverse,  and  is  controlled  by  the  single  lever 
to  the  rear  of  the  steering  wheel.  Fuel  for  the  motor  is  carried  in 
the  receptacle  in  front  of  the  dash-board.  It  is  claimed  that  this 
device  permits  easy  motion  of  the  vehicle  and  absolute  control, 
together  with  ready  steering  qualities.  An  American  invention 
of  somewhat  similar  description  is  the  International  Motor 
Wheel,  which  is,  briefly,  a  single  forward  drive  wheel,  carrying 
on  its  frame  a  double  cylinder  gasoline  motor  and  its  fly-wheel. 
The  frame  may  be  clamped  to  the  front  of  any  vehicle,  which  may 
be  steered  by  a  brake-wheel  working  on  a  spur  gear.  One  ad- 
vantage of  the  device  is  that  no  reverse  contrivance  is  necessary ; 
the  wheel  needing  only  to  be  turned  completely  around  in  order 
to  back  the  carriage  when  the  motor  is  started. 

The  American  Bicycle  Co.  recently  put  on  the  market  a  three- 
wheeled  carriage — the  "Trimoto" — capable  of  seating  two  per- 
sons and  giving  a  speed  of  twelve  miles  per  hour.  As  in  the  last- 
named  contrivance,  the  motor,  as  well  as  the  gasoline  receptacle, 
are  slung  on  the  frame  of  the  forward  single  wheel.  Steering  and 
motor  control  are  both  achieved  by  a  single  lever  coming  to  the 
driver's  hand  over  the  dashboard. 


60 


SELF-PROPELLED    VEHICLES. 


The  Conditions  for  Good  Traction  and  Steering. — Such 
machines  as  above  described  work  very  well  on  good  and  level 
roads,  but,  as  a  general  principle,  hanging  the  motor  in  front  in- 
volves insufficient  traction  and  causes  the  forward  wheel  to  skid 
even  on  slight  hills,  when  the  weight  is  mostly  over  the  rear  axle. 
In  the  early  days  of  motor  carriage  construction  it  was  com- 
monly believed  that  overloading  the  rear,  or  drive-wheels,  in- 
volves skidding,  whereas  the  reverse  is  true,  and  at  the  present 


FIG.  59. — Front- Driving  Brougham  of  the  Electric  Vehicle  Co.,  used  in  New  York  City. 
This  model,  which  is  no  longer  manufactured,  represents  a  construction  very  suitable 
for  city  service,  but  quite  inappropriate  for  country  and  general  use. 

time  the  rule  is  to  make  them  carry  the  greater  part  of  the  load, 
in  order  to  promote  traction.  It  is  obvious,  then,  that  the  rear 
axle  is  most  logically  the  drive  axle,  since,  when  ascending  hills 
the  bulk  of  the  weight  must  come  upon  it  on  any  theory  of  con- 
struction. Moreover,  it  must  also  properly  be  the  load-carrier, 
since,  as  has  been  frequently  demonstrated,  any  attempt  to  place 
the  greater  weight  in  front  only  complicates  difficulties.  Car- 
riages constructed  to  carry  the  load  on  the  front  axle  have  fre- 
quently exhibited  the  tendency  to  slip  sideways,  particularly 
when  the  brake  has  been  suddenly  applied.  It  has  not  been  an 


COMBINED   STEERING   AND    DRIVING. 


61 


uncommon  thing  that  such  carriages  would  turn  completely 
around  on  a  greasy  street,  when  propelled  by  sufficient  power  to 
cause  the  wheels  to  slide.  It  has  also  been  found  that  any  ar- 
rangement that  will  prevent  slipping  forward  will  also  do  away 
with  the  danger  of  slipping  sideways.  Hence,  a  well-loaded  rear 
driving  axle  may  be  considered  a  permanence,  not  to  say  a  practi- 
cal necessity  in  motor  carriage  construction, 


AUTOMOBILE  TOPICS. 

FIG.  00  — Anti-skidding  device  on  the  rear  wheel  of  a  Mercedes  limousine.  A  net- 
work of  braided  rope  offers  sufficient  resistance  to  prevent  side-step  and  skidding 
on  a  greasy  street. 


CHAPTER  six. 

THE   UNDERFRAMES   OF  MOTOR   CARRIAGES. 

Frames  for  Motor  Carriages.— In  general,  it  may  be  said, 
the  problems  involved  in  the  construction  of  motor  carriage 
underframes  are  comparatively  simple.  They  must  embody 
lightness  and  strength,  firmness  and  some  flexibility,  and  suffi- 
cient solidity  to  resist  the  destructive  effects  of  motor  vibration. 
The  last-named  consideration  is  of  particular  importance  in  the 
construction  of  gasoline  carriages,  but  is  to  a  certain  extent  true 
also  of  steam  carriages,  since  even  with  the  best-constructed  en- 
gine of  the  latter  variety,  the  long-continued  stress  of  vibration 
is  liable  to  produce  strain  and  breakage,  if  not  properly  calcu- 
lated. In  other  particulars  the  frame  of  a  horse-drawn  vehicle  is 
fairly  typical,  except  in  so  far  as  the  conditions  involved  in 
mounting  a  motor  necessitate  consideration  of  new  centres  of  re- 
sistance to  strain. 

Horse  Carriages  and  Motor  Carriages.— The  general  situa- 
tion as  regards  the  constructional  relations  of  the  underframes 
for  horse  carriages  and  motor  carriages  has  been  summed  by  Mr. 
Woods,  as  follows :  "The  trouble  has  usually  been  that  engineers, 
electricians  and  mechanicians  have  been  the  original  authors  of 
the  automobile,  and  their  minds  have  been  so  concentrated  upon 
the  development  and  perfection  of  the  mechanical  and  electrical 
parts  that  they  have  entirely  ignored  the  artistic  side  of  it.  This 
was  undoubtedly  brought  about  by  the  indifference  and  skepti- 
cism, as  well  as  opposition,  offered  the  advancement  of  the  motor 
vehicle  from  legitimate  carriage  manufacturers,  to  whom  such 
men  refrained  from  going  for  advice.  There  is  no  question  but 
that  this  problem  belonged  to  the  carriage  manufacturers,  and, 
had  they  taken  hold  of  it  in  time,  they  would  have  preserved 
to  themselves  an  industry  which  they  rightly  had  earned  by  prior 
experience  and  conceptions  as  carriage  producers.  *  *  *  * 
Another  point  of  construction  is  bicycle  tubing,  or  tubing  of  that 
nature,  for  frame  work  or  running  gears — in  other  words,  bicycle 


Of  MOTOR   CARRIAGES,  83 

Construction  for  supporting  the  carriage  and  its  weight,  as  com- 
pared with  regular  and  well-known  carriage  methods  of  construc- 
tion. Tubing  can,  without  doubt,  be  made  strong  enough,  but 
that  is  not  the  question  altogether.  We  must  have  the  entire 
carriage  construction  in  such  shape  that  it  can  be  repaired  by 
the  same  class  of  artisans,  blacksmiths,  etc.,  that  is  now  employed 
by  the  carriage-makers  throughout  the  country.  ***** 
A-  motor  vehicle  should  be  constructed  in  all  of  its  iron  work, 
its  running  gear  and  axles,  the  method  of  putting  on  its  springs, 
etc.,  as  nearly  as  possible  after  the  methods  now  in  existence  in 
the  carriage  world,  using,  as  far  as  practicable  throughout  the 
vehicle,  standard  carriage  hardware.  In  this  way  the  purchaser 
of  an  automobile  has  a  resource  at  his  own  door  for  such  repairs 
as  he  may  need  from  year  to  year  in  addition  to  his  regular  paint- 
ing, varnishing  and  trimming  repairs." 


Steel  Tubing  Framework.— There  are  two  principal  ob- 
jects sought  in  the  use  of  tubular  frame\vork  for  motor  carriages 
— strength  and  lightness.  These  desiderata,  which  are  possible 
in  cycles  only  with  this  style  of  construction,  are  less  prominent 
in  automobiles.  Thus  it  is  that,  while  the  majority  of  European 
machines  still  adhere  to  its  use,  there  is  a  strongly-marked  ten- 
dency in  America  toward  angle  iron  frames,  and  even  more  fa- 
miliar combinations.  By  the  use  of  brazed  joints  tubular  frame- 
work is  rendered  immensely  strong ;  for,  as  is  asserted  by  numer- 
ous bicycle  authorities,  breakage  practically  never  occurs  at  the 
joints.  But  to  properly  repair  damage  requires  the  insertion 
and  brazing  of  fresh  tube  lengths,  which,  itself,  involves  special 
facilities.  Another  objection,  obviously  to  be  derived  from  ex- 
isting tubular  structures,  is  that  the  advantages  gained,  in  point 
of  combined  strength  and  lightness,  are  very  largely  neutralized 
by  the  necessity  of  extra  bracing  and  greater  complexity,  quite 
readily  escaped  with  the  use  of  angle-iron  framework.  Thus  it  is 
that  Mr.  Woods,  as  above  quoted,  can  assert  that  tubular  frame- 
work in  a  4,900  pound  electric  cab  saves  onlv  about  200  pounds 
weight,  while,  as  we  may  readily  discover,  the  desirable  end  of 
simple  structure  is  not  particularly  advanced.  Furthermore,  the 
aesthetic  considerations  of  the  situation  are  rather  against  a  prac- 


64 


SELF-PROPELLED    VEHICLES. 


tice  necessitating  the  use  of  clumsy-looking  pipes,  when  lighter 
structures  can  quite  as  readily  subserve  the  same  ends. 

The  Stanley  Tubing  Underframe. —  The  Stanley  underframe, 
used  in  the  ''Locomobile"  and  several  other  steam  carriages  is 
one  of  the  most  representative  constructions  of  its  class.  As 
shown  in  the  accompanying  figure,  the  front  and  rear  axle  shafts 
are  inserted  into  straight  cross  tubes,  which  are  brazed  to  arched 
cross  tubes,  intended  to  lend  additional  strength  and  serve  as 
supports  for  the  longitudinal  reach  tubes.  These  reach  tubes, 
two  in  number,  are  swivel-jointed  to  the  arched  cross  tubes,  as 


FIG.  61.— The  Stanley  Type  of  Underframe  used  on  the  "  Locomobile  "  and  several  other 

Carriages. 

shown,  and  further  secured  in  place  by  stay  pieces  swiveled  at 
the  four  corners  of  the  frame  and  ring — jointed  loosely  on  the 
reach  tubes.  This  construction  permits  some  flexibility  on  rough 
roads.  The  rear  cross  tube  is  divided  at  the  centre  to  admit  the 
sprocket  and  brake  drum,  with  the  contained  differential  gear. 
As  additional  security  the  two  ends  are  rigidly  joined  to  the 
arched  tube  by  perpendicular  stay  rods,  and  connected  together 
by  a  nearly  circular  guard  plate  surrounding  the  sprocket  and 
brake  drum.  The  forward  arched  cross  tube  supports  the  for- 
ward spring,  which  is  fixed  transversely  under  the  body  of  the 
carriage,  and  in  front  of  the  vertical  axis  post  of  the  steering  lever. 
The  rear  springs  are  arranged  longitudinally  on  either  side  of  the 
carriage,  being  bolted  to  the  seats  shown  half  way  on  the  curve 


VNDERFRAMES   OF  MOTOR    CARRIAGES.  65 

of  the  rear-arched  cross  tube.  The  boiler  and  engine,  as  may  be 
seen  in  a  later  figure  of  the  "Locomobile"  carriage — and  this  is 
the  most  approved  arrangement  for  motors  of  every  variety — are 
disposed  within  the  body,  beneath  and  to  the  rear  of  the  seat, 
forward  of  the  rear  axle.  This  arrangement  overcomes  many 
difficulties  involved  in  attaching  them  direct  to  the  underframe, 
and  is  perfectly  practicable;  since  the  springs,  in  compression, 
move  in  a  line  tangential  to  the  circumference  of  the  sprocket 
wheel,  thus  merely  shifting  the  radial  line  between  the  sprocket 
wheel  and  pinion,  and  enabling  the  chain  to  transmit  the  power 
without  interruption.  This  could  not  be  the  case  were  the  motor 


FIG.  62.— The  Flexible  Underframe  of  the  Reading  Steam  Carriage. 

suspended  immediately  above  the  sprocket,  nor  would  the  effect 
of  steady  driving  be  any  better  achieved  by  suspending  it  on  the 
underframe  below  the  springs,  as  is  still  done  by  some  manufac- 
turers. 

The  Reading  Tubular  Frame.— Another  tubular  frame,  also 
intended  for  steam  carriage  use,  is  shown  in  the  accompanying 
figure.  In  it,  as  in  the  Stanley  frame,  there  are  transverse  axle 
tubes  at  front  and  rear,  the  latter  being  similarly  divided  at  the 
centre  for  the  sprocket  and  brake  drum.  The  longitudinal  reach 
rods,  however,  instead  of  running  parallel  and  at  right  angles  to 
the  axles,  are  disposed  so  as  to  form  a  nearly  complete  triangle, 
with  the  forward  axle  tube  as  the  base  and  the  sprocket  near  the 
apex.  -The  joints  on  the  forward  axle  are  swiveled,  and  on  the 


63  S&L&PROPELLED    VEHICLES* 

rear  axle  are  ring  pivots,  so  as  to  permit  the  distortion  shown  in 
the  figure  on  rough  or  uneven  roads.  The  stay  rods  at  either  side 
of  the  reach  tubes,  joining  them  to  the  rear  axle  tube,  are  also 
pivoted,  as  shown,  thus  assisting  the  flexibility,  while  increasing 
the  strength.  The  forward  arched  cross  tube  of  the  Stanley  frame 
is  replaced  here  by  a  semi-elliptical  spring,  while  the  same  feature 


FIG.  63.— The  Tubular  Flexible  Underframe  of  the  McKay  Carriage,  showing  the  double 
swivel  jointed  front  axle. 

on  the  rear  axle  is  here  made  continuous  with  the  axle  bearings, 
to  which  are  brazed  the  centre-divided  axle  tubes,  the  three  being 
connected  and  brazed  to  stay  rods.  The  rear  spring,  also  semi- 
elliptical,  is  jointed  to  the  arched  cross  tube  near  the  rear  axle 
bearings.  The  rear  axle  shaft,  however,  is  rigid  with  the  car- 
riage body  containing  the  motor,  so  that  no  distortion  of  the  kind 
pictured  can  interfere  with  the  steady  drive. 

Other  Flexibility  Devices. —  Several  other  carriages  attain  the 
end  of  a  flexible  and  distortible  underframe  by  a  three-point  sup- 
port and  a  swivel  joint  at  the  centre  of  the  forward  axle  shaft. 
This  gives  the  same  general  effect  on  uneven  roadways,  as  is 
shown  in  the  figure  of  the  Reading  carriage,  allowing  the  four 
wheels  to  run  on  different  planes,  but,  as  is  held  by  some  authori- 
ties, it  is  not  as  efficient  in  absorbing  undue  vibration,  as  some 
system  of  jointure  involving  a  four-point  support.  It  has,  how- 


OP  MOTOR  CAX&IAG&S.  6? 


FIG.  64.— Plan  of  the  De  Dion  &  Bouton  Underframe  and  Running  Gear,  showing  the 
•     motor  and  mechanism  in  position.    A,  Motor;  B,  Vaporizer;  C,  Change  of  Speed;  D, 
Differential;    F,  Curved    Axle;    G,  Auxiliary  Brake:    I,  Variable  Speed   Controller 
and  Brake;  J,  Steering  Handle;  K,  Muffler;  L,  Radiator. 


68 


SELF-PROPELLED    VEHICLES. 


ever,  been  adopted  with  apparently  good  results  in  carriages  oi 
all  descriptions.  The  "Steamobile"  steam  carriage  has  the  reach 
rods  coming  together  in  an  angle  to  the  front  of  the  frame,  and 
swiveled  at  the  centre  of  the  forward  axle  shaft  in  a  yoke,  which 
carries  the  axle  and  allows  it  even  greater  play  in  passing  over 
obstructions  than  is  possible  even  with  other  methods  of  swivel- 
ing.  In  this  carriage  the  forward  spring  is  of  the  usual  elliptical 
construction,  placed  transversely,  or  parallel,  to  the  axle  shaft, 


FIG.  65.— Angle  Iron  Underframe  witii  swivel  joint  at  centre  cf  front  axle. 

and  attached  at  the  top  of  the  swivel  yoke.  This  arrangement  is 
fairly  typical  of  the  usual  three-point  support  construction,  and 
has  been  frequently  criticised,  because  one  spring  must  absorb 
all  the  jar  incident  to  the  raising  or  lowering  of  the  wheels. 
One  make  of  electric  carriage,  manufactured  in  Buffalo,  N.  Y., 
uses  the  centre-swiveled  forward  axle  shaft,  to  which  are  at- 
tached elliptical  springs  at  either  side,  running  with  the  length  of 
the  frame.  The  result  is  that,  by  the  use  of  extra  flexible  springs, 
vibration  is  so  reduced  as  to  permit  the  use  of  very  small  rubber 
tires,  while  in  no  way  diminishing  the  effect  of  a  flexible  frame. 


UNDERFRAMES  OF  MOTOR   CARRIAGES.  69 

The  Riker  Underframe.— One  of  the  best  known  devices  for 
securing  a  flexible  underframe  is  embodied  in  the  Riker  electric 
carriages.  The  construction  is  of  seamless  steel  tubing  through- 
out, and  includes  two  axle  shafts  and  a  cross  bar,  all  parallel  in 
the  width  of  the  frame,  and  two  longitudinal  reach  tubes,  each 
bent  inward  and  carried  forward  toward  the  front  of  the  carriage, 


Fio.  66.— The  Riker  Underframe,  showing  the  swivel  connections  at  front  and  rear  to  per- 
mit distortion  on  uneven  roads. 


thus  forming  a  rectangle  of  diminished  width  at  the  front  end. 
Both  the  reach  tubes  are  ring-jointed  over  the  forward  axle  tube ; 
one  being  securely  brazed  in  place,  the  other,  with  its  attached 
stay  tube  being  free  to  turn,  so  as  to  admit  of  raising  or  lowering 
the  axle  shaft,  without  straining  the  frame.  Both  the  reach  tubes 
have  their  rear  ends  inserted  in  bosses  below,  and  cast  in  one 
piece,  with  the  bearings  for  the  rotating  rear  axles  being  held  in 
place  by  collars  in  front  and  screw  nuts  at  the  rear.  These  bosses 
are  thus  true  bearings,  permitting  a  certain  rotary  movement  of 
the  reach  tubes  in  the  effort  to  accommodate  the  axles  to  any 
unevenness  in  the  roadbed.  The  contour  of  the  frame  is  main- 
tained by  binding  collars  at  the  jointure  of  the  movable  reach 
tube  on  the  forward  axle,  and  by  the  transverse  cross  tube  at- 


70 


SELF-PROPELLED    VEHICLES. 


tached  midway  in  the  length  of  both.  As  shown  in  the  diagram 
of  this  tmderframe,  the  motor  is  suspended  between  the  rear  axle 
tube,  which  forms  a  sleeve  over  the  rotating  centre-divided  axle, 
and  the  midway  cross  tube,  already  mentioned  as  forward  of  the 
axle  shaft.  The  effect  of  a  steady  drive  is  obtained  by  attaching 
the  motor  and  gearing  at  the  same  side  of  the  frame  with  the 
rig-idly  attached  and  braze-jointed  reach  tube,  so  that  the  flexi- 
bility which  permits  a  certain  degree  of  distortion  in  passing  over 


FIG.  67  —Plan  of  the  Duryea  Three-wheeled  Phaeton,  showing  the  body  frame  used  as 
attachment  for  all  working  parts,  dispensing  with  the  underframe  entirely. 

uneven  roadbeds,  through  the  loose  attachments  of  the  opposite 
reach,  in  no  way  interferes  with  the  interaction  of  the  driving 
gears.  Herein,  we  see  a  fundamental  constructional  principle  for 
a  flexible  motor  carriage  frame ;  that  the  flexible  and  distortable 
portion  should  involve  only  that  the  forward  and  rear  axle  shafts 
may  be  so  twisted  as  to  move  on  different  planes,  thus  insuring 
the  stability  of  the  carriage  body,  while,  at  the  same  time,  main- 
taining the  motor  and  drive  axle  in  a  fixed  and  invariable  rela- 
tion. 

Dispensing  with  the  Underframe. — The  tradition  has  be- 
come so  fixed  among  builders  and  users  that  an  elaborate  and 
strongly-constructed  underframe  is  indispensable  to  an  efficient 


UNDERFRAMES  OF  MOTOR   CARRIAGES. 


71 


and  easy-running  automobile  carriage  that  any  proposition  to 
dispense  with  it  altogether  will  likely  be  scouted  as  impracticable. 
As  a  matter  of  fact,  however,  one  of  the  most  efficient  makes 
of  American  gasoline  carriage— the  Duryea  Power  Co.'s  phaeton 
—avoids  the  added  weight  and  strength  of  the  frame  by  the  sim- 
ple device  of  hanging  the  axles  directly  on  the  springs  support- 


FIG.  68.— Duryea  Four-wheeled  Trap.  This  carriage,  like  all  others  made  by  the  Duryeas, 
has  no  underf  rame ;  the  strongly  built  body  serving  as  a  frame  to  which  the  axles 
and  springs  are  hung. 

ing  the  body,  which  is  unusually  strongly  and  heavily  built.  This 
practice,  following  closely  on  the  general  plan  of  light  horse 
phaetons,  enables  the  use  of  a  heavier  motor  and  body,  with  all  the 
involved  advantages,  while  at  the  same  time  allowing  the  full  use 
for  driving  of  much  of  the  power  ordinarily  absorbed  in  propel- 
ling a  heavily-built  running  gear.  The  needed  effect  of  flexibility 
is  secured  by  extra  long  and  resilient  springs,  a  semi-elliptical 
pair  running  longitudinally  over  the  rear  axle  shaft,  and  a  semi- 
elliptical  single  spring  running  transversely  over  the  forward 


72  SELF-PROPELLED    VEHICLES. 

shaft.  The  accompanying  diagram  plan  of  the  Duryea  three- 
wheeled  carnage  and  the  view  of  a  four-wheeler  display  the  con- 
structional points  to  advantage.  As  we  shall  see  later  these  are 
the  same  in  both,  excepting  on  the  forward  wheels. 

Three-Wheeled  Carriages. —  While  most  of  the  best  known 
makes  of  motor  carriage  run  on  four  wheels,  like  or- 
dinary horse-drawn  vehicles,  there  are  several  arguments 


FIG.  69. — Angle  Iron  Underframe  of  the  Knox  Three-wheeled  Gasoline  Phaeton,  showing 
motor  and  gearing  in  position,  also  steering  connections. 

in  favor  of  using  three-wheelers.  One  of  the  most  prom- 
inent constructional  considerations  is  that  the  principle  of 
"three-point  support"  largely,  if  not  altogether,  does  away  with 
the  necessity  of  a  flexible  underframe  to  adjust  the  wheel  levels 
on  uneven  roads,  with  the  result  that,  as  is  claimed  by  one  manu- 
facturer, there  can  be  no  "unequal  strains  in  the  frame,  tending  to 
break  or  twist  it,  or  disalign  the  machinery."  All  the  advan- 
tages of  a  rigid  frame,  which,  as  we  have  already  seen,  must  bo 
in  some  way  combined  with  a  flexible  frame,  in  order  to  obtain 
an  invariable  relation  between  the  motor  and  the  drive  axte,  are 
thus  possible  without  sacrifice  of  other  qualities  equally  essen- 
tial. It  is  claimed,  however,  that  three-wheelers  are  more  liable 


UNDERFRAMES  OF  MOTOR   CARRIAGES.  73 

to  upset  than  are  carriages  with  four  wheels,  which  would  very 
likely  be  the  case  were  an  attempt  made  to  elevate  one  rear  wheel 
at  too  great  an  angle.  But,  as  may  be  readily  understood,  a  four- 
wheeler  would  be  no  more  stable  under  such  unusual  conditions, 
which  would  tend  either  to  upset  the  carriage  or  twist  the  under- 
frame  entirely  out  of  shape.  There  is  some  show  of  reason,  then, 
in  the  assertion  that  a  three-wheeler  will  travel  on  any  road 


FIG.  70.— The  Knox  Three-wheeled  Gasoline  Phaeton,  showing  angle  iron  underframe, 
three-point  support  and  steering  connections. 

passable  to  a  four-wheeled  carriage.  For,  provided  the  carriage 
be  properly  designed,  and  the  proportions  of  breadth,  length  and 
height,  the  weight  of  the  machinery  and  body,  and  the  distribu- 
tion of  the  load  be  accurately  calculated,  the  danger  of  an  upset 
in  passing  over  any  inequality  that  a  sensible  driver  is  capable  of 
attempting  would  be  exceedingly  remote. 

Advantages  of  Three- Wheelers.— In  a  letter  to  the  "Horseless 
Age,"  Mr.  Charles  E.  Duryea,  of  the  Duryea  Power  Co.,  says : 
"The  writer  is  free  to  predict  that  the  future  popular  two-passen- 
ger carriage  will  be  a  three-wheeler,  because  of  the  many  ad- 
vantages which  only  need  to  be  known  to  be  appreciated.  We 
are  running  three  and  four-wheelers  of  the  same  design,  side  by 
side  over  all  kinds  of  roads  in  this  locality,  and  know  by  actual 
comparison  that  the  three-wheeler  is  preferable  in  most  cases.  We 


74  SELF-PROPELLED    VEHICLES. 

submit  that  actual  tests  are  stronger  proofs  than  theories."  In 
the  same  letter  he  says  further:  "The  three-wheeled  carnage,  if 
properly  designed,  rides  as  easy  as  a  four-wheeler,  or  so  nearly  so 
that  the  difference  cannot  be  told  by  a  blindfolded  observer  riding 
in  the  two  alternately;  while  the  three-wheeler  steers  more  easily, 
requires  less  power  to  propel,  starts  and  stops  more  quickly,  is 
simpler,  lighter,  very  much  better  in  mud  and  appreciably  better 
everywhere  else."  In  another  letter  on  the  same  subject  he  says  : 


Pio.  71. — Duryea  Three-wheeled  Delivery  Wagon.    This  wagon  is  built  on  the  plan  shown 

in  Fig.  67. 

"While  we  supply  four-wheelers  to  those  buyers  who  do  not  wish 
the  three-wheeler,  we  are  confident  that  the  three-wheeler  is  the 
best  machine  of  the  two,  and  have  demonstrated  the  same  many 
times  by  actual  comparison.  There  is  one  less  tire  to  watch, 
fewer  parts  to  look  after,  less  weight  to  carry,  one  less  track,  and 
consequently  less  road  friction,  which  means  less  fuel,  less  heat, 
less  noise."  It  has  also  been  claimed  that  three-wheeled  car- 
riages have  the  additional  advantage  of  vibrating  less  on  rough 
roads,  some  claiming  a  decrease  in  this  respect  on  a  ratio  of  3 
to  4.  But  this  is  not  so  certain,  according  to  other  findings.  The 
manufacturers  of  the  Knox  gasoline  three-wheeler,  which  is  en- 
joying an  increasing  popularity  in  some  quarters,  evidently  con- 
sider their  own  machine,  at  least,  highly  efficient  in  this  respect. 
They  say:  "We  use  the  principle  of  three-point  support 
*  *  *  wherever  possible,  the  frame  being  supported  on  three 
wheels,  the  engine  being  attached  to  the  frame  at  three  points, 


UNDERFRAMES   OF  MOTOR   CARRIAGES.  75 

and  the  body  being  mounted  on  the  frame  by  three  springs. 
Rough  or  uneven  roads  have  little  power  to  harm  such  con- 


Steering  Gear  of  the  Knox  Carriage.— With  the  use  of  four 
wheels,  as  we  have  already  seen,  ready  and  positive  steering  may 
be  attained  by  observing  a  few  simple  and  obvious  constructional 
principles,  prominent  among  which  is  the  requirement  of  keeping 
the  balance  of  leverage  as  near  the  axis  of  the  wheel  as  possible. 
This  end  is  made  even  more  practicable  with  a  three-wheeled 
vehicle  by  hanging  the  forward  single  wheel  on  a  fork,  after  the 
manner  of  an  ordinary  foot-propelled  bicycle.  Such  a  course  is 
actually  followed  in  the  Knox  carriage,  for  which  the  manufac- 
turers claim  "easy  and  reliable  steering"  with  the  following  ad- 
vantages:  "The  steering  action  is  the  same  as  in  a  bicycle  that 
can  be  ridden  'hands  off' ;  closest  possible  connection  from  hand 
of  operator  to  steering  wheel ;  entire  absence  of  levers  and  con- 
nections to  cause  lost  motion  or  trouble  to  operator ;  the  vehicle 
will  turn  in  a  nine-foot  circle  under  its  own  power;  very  short 
turns  may  be  made  at  high  speed  without  danger  of  capsizing." 
Even  with  all  the  excellent  features  above  enumerated,  it  is 
doubtful  if  the  method  of  controlling  the  steering  wheel  by  a 
lever  attached  direct  to  the  pivot  of  a  swinging  wheel  is  alto- 
gether the  best  construction  for  a  motor  vehicle.  For,  as  is  evi- 
dent on  reflection,  a  hand  lever  of  sufficient  length  to  give  the 
steerer  a  positive  turn,  without  using  too  much  strength,  will 
describe  an  arc  of  such  dimensions  as  to  annoy  the  riders  and 
often  necessitate  long  reaches.  It  is  possible  that-  some  form  of 
worm  gear  and  pinion  device  would  achieve  all  the  excellent  re- 
sults claimed  without  the  difficulties  involved  in  a  long  lever. 

Duryea's  Steering  Head  — The  steering  wheel  of  the  Duryea 
three-wheeler  is  not  hung  in  a  fork,  but  turns  on  an  axle  shaft 
attached  to  the  two  curled  bars  extending  to  the  front  of  the  car- 
riage body.  In  all  respects,  therefore,  the  three-wheeler  of  the 
Duryea  Co.  differs  from  the  four-wheeler  only 'in  the  fact  that 
a  single  wheel  is  thus  attached,  instead  of  the  semi-elliptical 
spring,  carrying  a  through  axle  for  two  knuckle-jointed  wheels. 
The  steering  head  is  an  ingenious  and  highly  efficient  device. 


76 


SELF-PROPELLED    VEHICLES. 


which  has  been  in  use  on  these  carriages  for  nearly  four  years. 
As  shown  in  the  diagram,  the  forward  wheel  has  twelve  spokes 
mounted  on  mortises  on  a  malleable  ring,  in  which  are  screwed 
hardened  steel  ball  cones,  provided  with  a  locking  device  for  fas- 
tening after  adjustment.  This  malleable  ring  when  mounted  re- 
volves on  a  ball  race,  containing  thirty  three-eighth-inch  balls, 
which  is  screwed  to  the  cylindrical  steering  head.  At  the  top 


FIG.  72.— Steering  Head  of  the  Duryea  Three-wheeled  Carriages.  X  is  the  support  of  the 
wheel  which  turns  on  the  ball  race  shown.  Y  is  the  attachment  of  the  steering 
links. 


and  bottom  of  the  steering  head  are  mounted  hardened  cups  for 
the  steering  pivot  cones,  the  one  fixed  permanently,  the  other 
adjustably  in  the  cross  bar  or  support,  which  carries  the  front 
end  of  the  vehicle.  As  shown  in  the  diagram,  the  upper  cone 
may  be  screwed  in  or  out  to  adjust  the  bearing  at  this  point.  It 
is  held  in  place  by  a  clamp,  while  the  lower  cone  generally  turns 
on  balls,  as  shown.  By  this  arrangement  the  steering  pivot  is 
brought  directly  into  the  plane  of  the  wheel,  as  in  a  cycle,  so  that 
there  is  no  jar  on  the  steering  lever,  or  need  of  unusual  effort  on 
the  part  of  the  driver.  Moreover  the  arrangement  is  highly  effi- 
cient in  ensuring  a  constant  direction,  particularly  when  travel- 
ing on  level  roads,  a  point  highly  desirable  in  a  pleasure  car- 
riage. 


UNDERFRAMES  Of  MOTOR 


S&LF-PROPELLED 


The  Present  Situation  on  Frames. — Some  of  the  foremost 
manufacturers  of  motor  carriages  at  the  present  time  hold  to  the 
conviction  that  an  elaborate  underframe  is  rather  a  useless  com- 
plication than  an  advantage  in  any  sense.  This  means  that,  as 
is  being  increasingly  understood,  the  same  framework  may  serve 
for  the  body,  the  motor  and  the  running  gear,  giving  a  combina- 
tion that  is  lighter  and  stronger  than  where  two  or  three  separate 


FIG.  74.— Running  Gear  of  the  Charron  carriage ;  one  of  the  newer  makes  of  French 
automobiles,  constructed  on  the  general  models  of  the  Panhard-Levassor.  In 
this  carriage  the  running  gear  consists  of  a  heavy,  trussed,  wooden  body  frame 
to  which  the  wheels  are  hung  by  the  springs,  placing  the  machinery  entirely 
above  the  axles.  The  same  general  plan  is  followed  in  the  majority  of  heavy 
touring  cars,  although  some  manufacturers  use  channel  steel  frame  work.  Very 
few  large  cars  at  the  present  time  use  any  variety  of  tubular  underframe. 


frames  are  used,  besides  saving  space,  material,  labor,  care  and 
repairing,  and  increasing  the  neatness,  while  descreasing  the 
weight  and  the  cost.  The  body  must  be  mounted  on  springs,  and 
it  is  the  best  construction,  particularly  where  high  speeds  are 
contemplated,  to  mount  the  motor  in  the  body.  In  his  statement 
that  the  experience  of  carnage  builders  is  preferable  in  the  matter 
of  underframes,tothatof  bicycle  builders — for  it  was  entirely  from 
bicycle  precedents  that  tubular  framework  was  ever  adopted — 
Mr.  Woods  seems  to  be  in  accord  with  several  other  authorities. 
Even  with  the  most  carefully  planned  tubular  frame  the  stiffness 


UNDERFRAMES  Of  MOTOR  CARRIAGES,  79 

of  the  construction  is  poorly  compensated  even  with  the  use  of 
swivel  joints,  and  some  of  the  best  known  makes  of  motor  car- 
riage with  tubular  frames  are  constantly  giving  trouble  from  this 
cause,  involving  constant  damage  and  consequent  repairs.  On 
the  other  hand,  it  must  not  be  forgotten  that,  unlike  both  carriage 
and  cycle,  the  automobile  is  a  locomotive,  and  that,  as  such,  its 
peculiar  conditions  demand  constructions  to  which  no  former 
experience  is  precisely  analogous.  In  no  matter  more  than  un- 
derframes  is  it  so  essential  to  bear  this  distinction  in  mind,  and  in 
no  point  is  it  so  apparent  that  the  ultimate  or  permanent  type  of 
motor  carriage  will  depart  quite  entirely  from  the  precedents  of 
horse-drawn  vehicles.  In  a  letter  to  the  author,  Mr.  C.  E.  Dur- 
yea  says :  "The  use  of  steel  wheels  and  tubular  construction  is 
an  outgrowth  of  cycle  experience,  but  engineers  make  a  mistake 
who  attempt  to  apply  their  experience  indiscriminately  to  car- 
riages, for  the  carriage  problem  is  not  a  single-plane  problem. 
Both  the  cycle  and  its  wheels  receive  strains,  and  in  a  single 
plane,  while  cycle  riders  save  themselves  andv  the  machine  by 
standing  on  the  pedals  on  rough  spots.  The  automobile  rider 
never  does  this,  while  the  constant  torsions  and  wrenchings  of  a 
four-cornered  frame  are  simply  indescribable.  On  this  account 
a  three-wheeled  construction  is  much  longer  lived  and  will  un- 
doubtedly prevail  in  the  end." 


FIG.  74a.— An  American  Gasoline  Vehicle,  equipped  with  side  spring  frame,  after  the 
fashion  of  several  models  of  horse  carriage.  This  style  of  underframe  is  very  suitable 
for  light  motor  carriages,  overcoming  many  of  the  disadvantages  of  the  usual  spring 
constructions. 


CHAPTER  SEVEN. 

SPRINGS  AND    COMPENSATING    DEVICES  ;    RADIUS    RODS   AND 
JOINTED   SHAFTS. 

Springs  for  Motor  Carriages. — Like  all  varieties  of  vehicle 
at  the  present  day,  automobiles  have  the  body  suspended  from 
the  axles  or  underframe  on  suitable  springs.  With  them,  also, 
the  usual  function  is  subserved,  absorbing  and  counteracting  jars 
and  cumulated  vibrations  incident  on  roughness  in  the  roadway 
or  a  high  degree  of  speed.  In  the  present  state  of  the  motor  car- 
riage industry,  there  are  few  data  regarding  the  proportions  and 
construction  of  springs,  best  suited  for  different  purposes;  the 
matter  being  largely  one  of  empirical  considerations  and  practical 
experiment.  We  may  readily  understand,  however,  that  motor 
carriages,  being,  intended  primarily  for  high  degrees  of  speed,  in^ 
volve  conditions  and  considerations  found  in  neither  horse-drawn 
vehicles  nor  railroad  cars.  The  latter,  although  traveling  at 
speeds  often  100  per  cent,  greater  than  the  average  automobile, 
run  upon  an  even  and  comparatively  unresistant  roadway — the 
track  of  steel  rails — while  the  former,  although  built  for  the  ordi- 
nary highways,  as  are  automobiles,  are  seldom  calculated  for  any 
but  very  moderate  rates  of  speed.  Railroad  cars  must,  thus,  pro- 
vide against  a  maximal  speed,  with  a  minimal  road  roughness 
and  resistance ;  horse  carriages,  on  the  other  hand,  must  provide 
against  a  maximal  roughness  and  resistance  with  a  minimal  speed ; 
motor  carriages  must  be  able  to  attain  high  speeds  and,  at  the 
same  time,  resist  the  annoying  and  destructive  effects  of  road- 
ways, inevitably  irregular  as  to  resistance  and  other  conditions 
of  surface.  As  a  general  proposition,  therefore,  we  may  assert 
that  such  springs  as  will  promote  comfort  will  prevent  undue 
wear  and  tear  on  the  motor  and  parts,  which,  in  fact,  makes  the 
end  of  easy  riding  for  the  passengers  the  prime  consideration. 

The  Theoretical  Working  Unity. — In  no  part  of  construction 
is  it  more  essential  to  consider  the  road  and  the  vehicle  as  a 
working  unit  than  in  the  matter  of  calculating  for  springs,  and  in 


XADIVS  KODS  AMD  StfAfiTS.  81 

no  point  is  there  a  greater  element  of  uncertainty  and  a  greater 
variableness  in  running  conditions  to  render  all  calculations  un- 
reliable and  inexact.  The  general  situation  is  well  expressed  in  a 
recent  article  on  motor  vans  in  the  London  Engineer,  which  speaks 
as  follows : 

"The  prime  fact  with  which  engineers  have  to  deal  is  that  the 
success  or  failure  of  any  design  mainly  depends  on  the  nature  of 
the  road  on  which  the  van  is  to  be  worked.  The  V-slides  of  a 
planing  machine  are  integral  parts  of  the  whole.  The  permanent 
way  of  a  railroad  and  the  rolling  stock  constitute  together  one 
complete  machine.  In  just  the  same  way  the  King's  highway 
must  be  regarded  as  an  integral  part  of  all  and  every  combination 
of  mechanical  appliances  by  which  transport  is  effected  on  the 
road.  In  one  word,  if  we  attempt  to  dissever  the  road  from  the 
van,  we  shall  fail  to  accomplish  anything.  Two  or  three  years 
ago,  the  maker  of  a  steam  van  told  us  that  he  was  surprised  to 
find  how  little  power  was  required  to  work  his  van.  He  had  been 
running  it  on  wood-paved  streets.  A  week  or  two  later  on  he  was 
very  much  more  surprised  to  find  that  on  fairly  good  macadam 
after  rain  he  could  do  next  to  nothing  with  the  same  van.  In 
preparing  the  designs  for  any  van,  the  quality  of  the  roads  must 
not  for  a  moment  be  forgotten ;  and  it  will  not  do  to  estimate  the 
character  of  the  road  by  anything  but  its  worst  bits.  A  length 
of  a  few  yards  of  soft,  sandy  bottom  on  an  otherwise  good  road 
will  certainly  bring  a  van  which  may  have  been  doing  well  to 
grief.  Curiously  enough  we  have  found  this  apparently  obvious 
circumstance  constantly  overlooked.  This  is  not  all,  however.  A 
road  may  be  level,  hard,  and  of  little  resistance  to  traction,  and 
yet  be  very  destructive  to  mechanism.  This  type  of  road  is  rough 
and  "knobby" ;  it  will  shake  a  vehicle  to  pieces,  and  the  mischief 
done  by  such  roads  augments  in  a  most  painfully  rapid  ratio  with 
the  pace  of  the  vehicle.  Jarring  and  tremor  are  as  effectual  as 
direct  violence  in  injuring  mechanism.  Scores  of  examples  of 
this  might  be  cited.  One  will  suffice.  In  a  motor  van  a  long 
horizontal  rod  was  used  to  couple  the  steering  gear  to  the  lead- 
ing wheels.  The  rod  was  broken  solely  by  vibration.  It  was  re- 
placed by  a  much  heavier  and  stronger  bar.  That  was  broken  in 
much  the  same  way,  and  finally  guides  had  to  be  fitted  to  steady 
the  rod  and  prevent  it  shaking." 


S2  SELF-PROPELLED    VEHICLES. 

Points  on  Spring  Suspension — As  regards  the  suspension  of 
springs  of  horse-drawn  vehicles  and  automobiles,  the  careful  ob- 
server will  note  one  point  of  divergence  at  once.  When  elliptic, 
or  semi-elliptic,  springs  of  the  ordinary  description  are  used, 
he  will  see  that  in  most  light  horse  carnages  only  two  are  sus- 
pended, one  over  each  of  the  axle  shafts,  across  the  width  of  the 
carriage.  In  automobiles  of  every  build  and  motive  power,  while 
a  single  spring  may  be  thus  attached  to  the  forward  axle,  the 
rear  axle  supports  two,  one  at  each  side  of  the  frame,  and  run- 
ning in  the  length  of  the  carriage.  This  is  a  construction  found 
only  in  the  heavier  patterns  of  horse  drawn  carriages,  and  in  both 
cases  it  is  resorted  to  for  the  purpose  of  neutralizing  the  forward 
lunge  of  the  body,  inevitable  on  rough  roads  with  a  single  trans- 


Fio.  75.— Scroll  Bottom  Carriage  Spring,  half  elliptic,  showing  connections  by  links  and 

shackles. 

verse  elliptical  spring.  With  the  horse  carriage  of  the  heavier 
pattern  such  vibration  is  annoying  and  also  hurtful  to  the  body, 
frame  and  springs.  With  the  automobile,  however,  the  case  is 
even  graver ;  for  not  only  will  similar  results  follow  at  high  speed, 
but  the  proper  distance  between  the  motor,  usually  carried  in  the 
body  above  the  springs,  and  the  rear  axle  will  be  continually  dis- 
turbed, with  consequent  damage  to  sprocket,  chain  and  gears  and 
loss  of  a  steady  drive.  Thus,  in  carriages  which  have  no  other 
provision  against  this  tendency  of  the  rear  axle  to  throw  back- 
ward or  forward  under  the  stress  of  travel,  it  is  necessary  to  use 
a  device  known  as  a  distance  rod  to  maintain  a  fixed  distance  be- 
tween motor  and  drive  axle,  when  the  throw  of  the  springs  would 
otherwise  permit  it  to  be  disturbed.  The  better  method  of  over- 
coming this  danger  is  to  set  the  springs  in  the  length  of  the 
carriage,  as  just  described ;  for  thus  most  of  the  violent  jars  in 
this  direction  are  absorbed,  and  the  fixed  relation  of  motor  and 
axle  maintained,  without  rigid  attachments,  which  would  form 


SPXltfGS,  KADWS  RODS  AMD  StiAfiTS*  88 

Another  notable  occasion  of  accidents.  This  allows  the  springs 
to  lengthen  under  pressure  from  above  or  from  the  direction  of 
travel,  and  further  reinforces  against  sidewise  lunges,  which, 
however,  are  of  far  less  frequent  occurrence.  With  the  use  of 
transversely  arranged  elliptical  springs  on  both  axles  similarly 
troublesome  conditions  in  the  steering  mechanism  would  result ; 
the  turning  of  the  steering  lever  frequently  compressing  the 
spring  sufficiently  to  make  steering  uncertain,  and  the  numerous 
jars  of  the  vehicle  on  a  rough  road  or  at  high  speed  often  tending 
to  check  its  operation  altogether. 


Fio.  76.— Spring  and  Radius  Rod  of  the  Mors  Carriages.  The  rod,  A,  maintains  a  fixed 
distance  between  the  sprocket  pinion,  B,  and  the  wheel  axle,  C,  even  when  the  springs 
are  constantly  in  action.  This  carriage  also  has  a  device  for  varying  the  distance 
between  the  countershaft  at  B,  and  the  engine  pulley,  by  sliding  the  entire  shaft  for- 
ward or  back  under  impulse  from  the  screw,  D.  The  spring,  being  hung  on  links  at 
front  and  rear,  has  considerable  play,  up  and  down,  without  disturbing  the  fixed  rela- 
tion of  the  axle,  C,  and  the  counter-shaft,  B,  as  determined  by  the  radius  rod,  A. 

Dimensions  of  Springs — Of  the  four  varieties  of  springs  used 
in  vehicles  of  various  kinds — extensible  spiral,  compressible  spiral, 
coiled,  and  laminated  leaf  springs — the  last-named  has  been  found 
by  all  odds  the  most  suitable  for  automobiles  in  point  of  easy 
riding,  if  in  no  others.  Such  springs,  which  are  composed  of  a 
number  of  leaves  or  laminae  of  steel,  can  be  made  in  proportions 
suitable  for  light  or  heavy  loads,  by  varying  the  size  and  number 
of  the  layers,  without  involving  the  jolts  and  vibrations  inevitable 
in  any  but  the  heaviest  structures  of  the  other  descriptions. 
However,  apart  from  certain  well  ascertained  figures  on  the  static 
weight  of  the  load  and  the  size  and  tensile  strength  of  the  springs 
designed  to  carry  it,  there  are  no  reliable  data  regarding  the 
proper  proportions  of  springs  for  automobile  carriages.  As  we 
have  said,  this  is,  and  must  continue,  a  matter  to  be  governed 
most  largely  by  experiment,  apart  from  mathematical  calcula- 
tions, since  the  constantly  varying  conditions  of  automobile  travel 


84       .  SELF-PROPELLED    VEHICLES. 

preclude  exact  theory.  Among  these  variants  may  be  mentioned 
high  speeds  on  any  and  every  kind  of  road  and  the  use  of  pneu- 
matic tires.  The  matter  is  still  further  qualified  by  the  size  of 
the  tires  and  the  degree  of  inflation,  for  both  of  these  points  are 
important  in  modifying  the  stress  to  come  upon  the  springs.  In- 
deed, there  is  no  more  important  factor  in  the  high  speed  motor 
vehicles  than  the  rubber  tires,  although  the  properties  developed 
in  its  practical  operation  by  no  means  permit  its  use  on  vehicles 
without  suspension  springs  of  some  description. 

The  Effects  of  Pneumatic  Tires.  —The  use  of  pneumatic  tires 
on  a  vehicle  permits  the  absorption  of  considerable  vibration  and 
the  consequent  use  of  softer  springs  than  are  possible  with  steel 
tires.  One  reason  for  this  is  that  pneumatic  tires,  after  violent 
or  unusual  compression,  do  not  rebound,  as  even  the  best 
springs  will  do ;  whence  only  a  minute  portion  of  the  total  shock 
is  transmitted  from  them  to  the  springs.  On  the  other  hand, 
however,  they  have  a  certain  bouncing  motion  of  their  ^vn, 
which  is  imparted  to  the  running  gear,  and  will  occasion  an  an- 
noying back-jolt,  unless  suitable  springs  are  interposed.  This 
is  entirely  neutralized  by  the  use  of  properly  adjusted  springs, 
although  in  the  matter  of  adjustment  we  must  consider  the  size 
and  degree  of  inflation  of  the  tires,  the  weight  and  dimensions 
of  the  springs,  and  the  average  speed  used.  In  some  respects  a 
heavier  spring  gives  easier  riding  than  a  light  one,  since  the  lat- 
ter is  apt  to  bounce  disproportionately,  even  with  good  pneumatic 
tires,  when  the  road  is  somewhat  rough.  In  this  matter  some 
authorities  make  a  direct  comparison  with  the  action  of  pneu- 
matic tires  on  bicycles,  whose  ease  of  riding  at  high  speeds  has 
frequently  been  found  to  be  a  consideration  not  only  of  the  road 
surface,  but  also  of  the  degree  of  inflation  of  the  tires.  The  se- 
verity and  quality  of  the  jars  received  under  stated  conditions  is, 
therefore,  typical  in  these  particulars  of  the  stress  brought  upon 
the  springs  set  over  the  pneumatics  in  an  automobile. 

As  the  reader  or  any  careful  observer  may  readily  conclude 
from  the  facts,  pneumatic  tires,  if  properly  inflated,  while  a  great 
factor  in  easy  traction,  are  by  no  means  the  sole  requirement. 
While  they  absorb  much  vibration  unavoidable  in  steel-tired 
vehicles,  without  springs,  they  do  not  wholly  set  aside  the  rule 


SPRINGS,    RADIUS  RODS  AND   SHAFTS. 


85 


that  it  is  exceedingly  bad  construction  not  to  suspend  motors  and 
other  heavy  freight.  As  has  been  frequently  learned  at  consid- 
erable cost,  rubber  tires  will  not  prevent  broken  axles  when  the 
motor  is  hung  below  the  springs.  For  this  reason  many  manu- 
facturers use,  not  only  additional  springs  for  the  seats,  but  also 
doubly  suspend  the  moving  parts,  such  as  boilers  and  engines  in 
steam  carriages,  or  storage  batteries  in  electric  vehicles.  Fre- 
quently, however,  this  additional  precaution  acts  to  neutralize 
the  effect  of  the  springs  by  aggravating  jolts  instead  of  allowing 
them  to  be  properly  absorbed  as  would  .otherwise  happen. 

The  whole  situation,  as  regards  the  relation  of  springs  and 
pneumatic  tires,  may  be  understood  by  reference  to  common 
experience  with  bicycles.  As  is  generally  known,  unless  certain 


FIG.  77.— Forward  .Axle  of  the  Jeanteaud  Electric  Carriage,  showing  double  half  elliptic 
tsprings  with  connections  by  links  to  frame  and  body. 

ascertained  rules  are  observed  regarding  both  the  inflation  of 
the  tires  and  the  method  of  riding,  the  rider  is  liable  to  experi- 
ence a  series  of  annoying  jolts  and  vibrations  on  the  best-made 
roads.  Thus,  while  the  rear,  or  drive-wheel  tire,  is  usually  in- 
flated until  very  hard,  the  forward  tire  is  allowed  to  remain  con- 
siderably softer.  By  this  means  are  avoided  the  vibrations  which 
inevitably  follow  when  both  are  pumped  hard.  The  rider  soon 
learns,  also,  in  passing  a  street  crossing  or  a  hollow  in  the  road- 
bed, to  raise  himself  on  the  pedals,  in  order  to  escape  a  shock  of 
considerable  severity.  To  partly  obviate  this  necessity  and  "make 
all  roads  smooth,"  several  makes  of  bicycle  have  what  the  manu- 
facturers call  a  "cushion  frame,"  consisting  of  a  flexible  spiral 


86  SELF-PROPELLED    VEHICLES 

spring  inserted  in  the  tubular  support  of  the  saddle  post.  The 
result  is  that  the  rider  is  greatly  relieved  of  shocks  and  vibra- 
tions, the  spring  acting  to  absorb  most  of  the  bounding  action 
of  the  tires.  Nor  has  a  similar  result  been  otherwise  successfully 
achieved,  although  it  has  been  claimed  by  some  bicyclists  that, 
the  annoying  jolts,  due  to  a  hard  forward  tire,  are  greatly  re- 
duced when  a  moderate  load  or  a  child  is  carried  on  the  handle 
bars.  Imperfect  inflation  of  the  rear  tire  is  apt  to  strain  and 
loosen  the  spokes,  while  only  slightly  modifying  the  annoying  ef- 
fects of  travel  on  uneven  roadways.  The  bearing  on  the  situation 
of  automobile  construction  is  obvious.  For,  since  the  passen- 
gers cannot  mitigate  such  shocks  by  any  changes  in  position  or 
distribution  of  the  load,  properly  proportioned  springs  are  the 
only  resort. 

Condition  of  Spring  Dimensions. — In  judging  of  the  dimen- 
sions and  elasticity  of  springs  suitable  for  carriage  use  the  limit 
of  elasticity  must  be  carefully  considered  with  relation  to  the 
static  and  maximum  loads  to  be  carried  by  the  vehicle.  The 
static  load  is  the  dead  weight  of  the  vehicle  body  and  frame, 
together  with  that  of  the  passengers  and  other  freight,  estimated 
when  at  rest.  The  maximum  load  is  the  proportionately  increased 
weight  of  the  same  items,  with  relation  to  the  traction  effort  re- 
quired when  the  vehicle  is  running  at  its  highest  speed,  under 
test  conditions  as  to  road  roughness  or  hill-climbing  require- 
ments. Similarly,  the  ultimate  load  is  the  greatest  weight  pos- 
sibly carried  with  good  spring  action.  That  the  springs  should 
be  calculated  to  retain  the  elasticity,  or  have  the  ultimate  strength 
far  beyond  the  maximum  load,  is  obvious,  when  we  consider  the 
office  of  a  spring  in  any  aspect.  In  calculating  the  proportions 
of  springs  in  the  best  constructed  railroads,  it  is  usually  cus- 
tomary to  consider  the  maximum  load  as  twice  the  static  load. 
Whence  it  is  the  general  practice  to  estimate  the  fitness  of  a  given 
spring  for  its  work  as  equivalent  to  the  quotient  of  the  weight  of 
the  spring  divided  by  the  product  of  its  length,  between  the  ex- 
tremities of  the  longest  leaf,  and  the  number,  width  and  thick- 
ness of  the  other  several  leaves.  The  variable  nature  of  carriage 
roads  makes  the  proportion  of  static  and  maximum  load  much 
higher  for  horse-drawn  vehicles  than  for  railway  cars,  except 


SPRINGS,   KADI  US  RODS  AND   SHAFTS.  87 

where  only  the  most  moderate  speeds  are  to  be  used,  but  for 
automobiles,  always  calculated  for  high  speeds,  it  never  falls  be- 
low a  ratio  of  i  to  3,  and  is  often  estimated  as  high  as  I  to  5. 
As  has  been  pointed  out  by  several  authorities  on  the  subject, 
the  difficulty  of  obtaining  springs  for  automobiles,  which  shall 
be  serviceable  under  all  conditions,  is  greatly  aggravated  when 
the  weight  of  the  body,  motors,  etc.,  is  very  much  in  excess  of 
that  of  the  passengers  provided  for.  This  is  true,  since  a  spring 
that  will  subserve  the  end  of  easy  riding  under  usual  conditions, 
with  extra  heavy  accessories  of  this  description,  would  permit 


FlO.  78.— Jar-absorbing  Spring  Control  Apparatus  used  on  the  Peugeot  carriages. 
Here  the  arm,  C,  is  jointed  to  A,  which  is  pivoted  to  the  frame  above  the  spring 
as  shown.  Arm,  D,  is  jointed  to  B,  which  is  pivoted  to  the  dead  axle  or  sleeve 
below  the  spring.  Both  C  and  D  work  upon  the  common  spindle,  E,  being  secured 
in  place  by  the  nut,  F,  adjusted  and  secured  in  place  by  a  bolt  at  G.  A  thick 
leather  washer  at  J  is  placed  between  the  disc,  H,  on  the  end  of  D,  and  a 
similar  disc  on  the  end  of  C,  while  the  spindles  of  A  and  B  move  on  thick  leather 
collars  ;  these  three  points  of  friction  resistance  serving  to  restrain  and  delay 
the  tendency  of  the  spring  to  resume  its  normal  position  after  each  depression, 
and  thus  absorbing  the  shocks  of  travel.  In  later  forms  of  this  apparatus  a 
strong  coiled  spring  is  substituted  for  the  leather  washer  at  J ;  either  device 
serving  equally  well  to  absorb  jars  and  control  the  action  of  the  springs,  accord- 
ing to  adjustment. 

no  end  of  jolting  and  annoying  vibration  at  high  speeds  on  im- 
perfecj  roads.  The  fault  is  difficult  to  discover  except  under 
test  conditions.  For  this  reason  builders  have  frequently  at- 
tempted to  counteract  the  uncertainties  of  spring  action  by  using 
extra  springs  on  the  seats,  somewhat  after  the  fashion  of  those 
used  in  some  rough  farm  and  draft  carts,  where  no  springs  at  all 
are  used  between  the  body  and  the  axletrees. 

As  a  general  rule,  also,  such  seat  springs  modify  the  practical 
rules  usually  followed,  permitting  the  use  of  even  lighter  springs 
to  support  the  body.  To  sum  up  the  general  requirements  in  a 


88  SELF-PROPELLED    VEHICLES. 

few  words,  we  may  say  that,  while  the  pneumatic  tires  will  often 
absorb  vibrations,  thus  permitting  soft  and  light  springs  under 
the  body,  the  occasional  inequalities  in  the  road  are  apt  to  occa- 
sion a  quick  succession  of  annoying  jolts,  reaching  by  accumu- 
lated forces  almost  to  the  limit  of  spring  elasticity,  or  succeed- 
ing one  another  so  rapidly,  at  high  speed,  that  the  springs  have 
little  time  to  recover  their  normal  shape.  This  seems  to  indicate 
that  a  heavier  spring  is  preferable,  or  else  that  spring  construc- 
tion must  be  in  some  way  varied  to  give  firmer  attachments  and 
more  evenly  distributed  elasticity;  the  time  required  by  the 
spring  to  recover  itself  being  the  same  under  all  conditions,  some 
springs  are  thus  unfit  for  high  speed  work.  Many  manufactur- 
ers prefer  semi-elliptical  springs  to  the  full  elliptical  on  the 
ground  that  their  elasticity  is  greater  for  a  given  weight  of  spring, 
and  the  consensus  of  opinion  on  the  latter  is  that  the  longer  the 
spring,  within  reasonable  limits,  the  greater  the  combined  elas- 
ticity and  lightness.  When  such  springs  are  used  as  side  sup- 
ports it  is  general  practice  to  attach  one  end  direct  to  the  longi- 
tudinal frame  and  connect  the  other  by  a  link,  thus  allowing  am- 
ple freedom  toward  lengthening.  When  placed  transversely  over 
the  forward  axle  both  ends  are  secured  to  links,  the  centre  being 
securely  clamped. 

Attachments  for  Springs — The  ends  of  ready  lengthening 
and  extra  elastic  support  are  also  accomplished  by  the  use  of 
what  are  known  as  scroll  elliptics  and  semi-elliptics,  wherein  one 
leaf  of  the  spring  is  extended  somewhat  at  one  end  and  turned 
over,  like  a  rolled  scroll,  to  be  connected  to  its  mate  or  to  the 
carriage  attachment  by  suitable  links  or  other  joint.  Links  are 
preferable  in  many  places  on  account  of  the  ready  action  allowed 
in  several  directions,  without  involving  tendency  to  yield  ueduly 
tinder  ordinary  conditions.  The  high  speed  requirements  of 
motor  carriages  makes  it  nearly  imperative  that  leaf  springs, 
either  half  or  full  elliptic,  should  be  securely  clamped  to  the  sup- 
ports by  clips  and  nuts,  rather  than  by  bolts  through  bolt  holes 
in  the  centre.  This  is  true  because  such  bolt  holes  are  liable 
to  prove  a  source  of  weakness  under  high  speed  conditions  and 
to  cause  the  breaking  of  springs  at  the  very  time  when  their  full 
strength  is  most  requisite.  With  clips  this  danger  is  wholly  avert- 


SPRINGS,   RADIUS  XODS  AND   SHAFTS. 


89 


ed,  and,  instead  of  a  weak  point  at  the  centre,  an  additional  rigid- 
ity and  re-enforcement  is  obtained. 

One  of  the  most  efficient  arrangements  of  springs  for  high 
speed  carriages  is  that  found  in  the  Jeanteaud  electric  car  and 
one  or  two  motor  carriages  of  American  make.  Two  semi-ellip- 
tical leaf  springs  are  clamped  together  at  their  centres,  leaving 
the  two  extremities  of  the  upper  one  in  position  for  attachment 
to  the  carriage  body,  and  the  two  extremities  of  the  lower  one  in 
position  for  attachment  to  the  axle.  Links  are  then  bolted  at  all 


FIG.  79.— The  De  Dion  &  Bouton  Spring  Compensating  Steering  Device.  The  V-shaped 
piece  A,  constructed  of  two  pieces,  as  shown,  is  attached  to  the  tubular  front  cross- 
piece  of  the  body  frame  at  D,  and  pivoted  on  the  ball  joint  at  F,  to  the  lower  V- 
shaped  piece,  B.  This  is  also  pivoted  at  F,  and  is  attached  to  the  axletree  at  E.  The 
T-piece,  C,  is  also  pivoted  at  E  rigidly  with  B,  so  as  to  turn  sideways  with  it.  It  car- 
ries the  links  C'  and  C",  which  actuate  the  steering  arms  of  the  two  stud  axles.  The 
link,  H,  is  attached  to  the  arm,  G,  and  when  moved  forward  or  back  by  the  worm 
gear  and  pinion  arrangement  at  the  base  of  the  steering-wheel  pillar,  moves  the  en- 
tire structure,  A.  B  and  C,  on  the  pivots,  D  and  E,  to  the  right  or  left,  as  desired. 
The  object  of  the  device  is  to  allow  of  a  certain  up  and  down  movement,  as  the 
springs  yield,  without  disarranging  the  steering  gear  or  vibrating  the  steer  wheel.  In 
such  cases  the  V-pieces,  A  and  B,  move  on  the  ball  joint  F,  thus  permitting  the 
points,  D  and  E,  to  be  approached  and  separated,  as  the  springs  move. 

four  points  in  order  to  suspend  the  springs  so  as  to  permit  the 
greatest  freedom  of  motion  laterally  and  allow  for  considerable 
compression. 

Construction  of  Springs. — The  leaf  springs  used  in  road  car- 
riages and  railroad  cars  consist  of  several  layers  of  steel  plates  or 
leaves  more  often  slightly  bent,  so  that,  when  laid  together,  they 


90 


SELF-PROPELLED    VEHICLES. 


are  found  forming  superposed  arcs  of  so  many  concentric  circles. 
It  is  essential  to  a  serviceable  spring  of  this  description  that  the 
line  of  the  arc  be  carefully  followed  from  end  to  end  of  each 
plate,  and  that  no  attempt  be  made  to  straighten  or  bend  back 
the  extremities  of  the  longest  leaves.  This  is  true  because  the 
spring  effect  is  derived  from  the  temper  of  the  metal  in  permitting 
the  load  to  flatten  all  the  arcs  at  once  under  a  single  stress,  which 
involves  that  they  should  slide  upon  one  another  in  altering  their 
shape,  as  could  not  be  the  case  were  there  any  such  departure 
from  the  line  of  the  arc,  as  has  been  mentioned.  In  that  case 
the  several  plates  would  tend  to  separate  and  "gape"  under  a 
load  requiring  a  degree  of  compression  tending  to  bring  the  ex- 
tremity of  any  arc  to  the  straight  portion  of  the  top  leaves.  The 


FIG.  80.— Jointed  Bear  Axle  of  the  De  Dion  &  Bouton  Carriages.  By  the  use  of  universal 
joints  between  the  driving  spur  and  wheel  spindles  a  steady  drive  may  be  maintained 
between  the  spur,  hung  on  the  body,  above  the  springs,  and  the  wheels,  below  the 
springs,  even  on  the  roughest  roads,  when  the  springs  are  constantly  in  action. 

result  would  be  a  loss  in  spring  action,  and  a  probable  source  of 
breakage  on  occasion.  In  constructing  laminated  leaf  springs  it 
is  essential  that  the  plates  should  decrease  on  a  regular  scale  of 
lengths,  in  order  that  the  structure  may  be  of  equal  strength 
throughout  and  of  sufficient  flexibility  for  the  loads  calculated 
to  its  dimensions.  Where  such  a  spring  is  thick,  consisting  of  a 
number  of  plates,  it  is  a  good  working  rule  that  the  ends  of  each 
several  plates  should  touch  the  sides  of  a  triangle,  whose  base  is 
drawn  between  the  extremities  of  the  longest  plate  and  whose 
apex  is  at  or  about  the  theoretical  centre  point  of  the  spring's 
movement.  This  means  that,  with  a  well-proportioned  spring  in 
its  normal  shape,  the  end  of  each  separate  plate  should  be  equi- 
distant from  that  of  the  one  immediately  above  it  and  of  the 
one  immediately  below  it.  By  this  construction  even  distribution 
of  stress  is  attained  without  waste  or  resistance  from  inactive 


SPRINGS,    RADIUS  RODS  AND    SHAFTS.  91 

portions  of  the  length  of  each  plate,  as  would  be  the  case  in  a 
laminated  spring  flattened  at  the  top  plate  and  having  the  longi- 
tudinal profile  shaped  to  an  arc.  Such  a  spring,  however,  would 
embody  bad  construction  in  another  particular,  since  it  would 
neglect  one  very  essential  feature  of  spring  construction — curva- 
ture of  the  plates.  This  curvature  is  intended  to  represent  the 
difference  between  the  spring  under  static  and  maximum  load ; 
at  the  latter  point  its  leaves  should  be  nearly  straightened  under 
stress ;  beyond  that  point,  as  they  are  bent  backward  and  down- 
ward, the  point  of  ultimate  strength,  involving  loss  of  elasticity 
and  breakage,  is  rapidly  approached.  It  follows,  therefore,  that 
the  end  of  a  perfectly  elastic  and  serviceable  spring  is  best  at- 
tained by  such  curvature  as  will  allow  bending  of  the  plates  from 
each  extremity  of  the  top  plates,  on  the  support  at  the  centre, 


FIG.  81.— Spring  Compensating  Steering  Device  used  on  the  Oldsmobile  Carriage. 
The  cut  shows  the  spindle  of  the  steering  lever  with  its  attached  arm  joining  the 
transverse  link  at  about  the  centre  of  its  length.  The  attachment  of  one  of  the 
side  springs  is  shown  near  the  right-hand  end  of  the  axle.  The  small  elliptical 
spring  takes  up  and  absorbs  the  vibrations  of  travel,  rendering  steering  positive 
and  uninterrupted. 

without  involving  endwise  compression,  as  is  the  case  when  the 
curve  approaches  a  semi-circular  contour.  Consequently,  lami- 
nated leaf  springs,  as  a  usual  thing,  are  constructed  to  an  arc  of 
never  more  than  ninety  degrees  and  often  very  much  less. 

Rules  for  Calculating  Springs.— Although  as  a  general 
proposition,  the  usefulness  of  a  spring  for  given  work  and  load 
is  strictly  a  consideration  of  the  total  length  of  the  structure  be- 
tween points  of  attachment,  the  thickness  and  number  of  the 
leaves,  and  the  quality  of  the  steel  used— the  last-named  consid- 


92  SELF-PROPELLED    VEHICLES. 

eration  is  of  the  utmost  importance — there  are  certain  formulae 
followed  in  railroad  work,  and  to  a  certain  extent,  in  carriage 
designing,  that  are  useful  to  the  practical  automobile  builder. 
As  given  in  several  works  on  locomotive  and  car  construction, 
they  may  be  summarized  as  follows: 

Let  B  represent  the  breadth  of  the  plates  in  inches. 

Let  T  represent  the  thickness  of  each  in  sixteenths  of  an  inch. 

Let  N  represent  the  number  of  plates  in  the  spring. 


FIG.  82.— Rear  Spring  used  on  the  Packard  Light  Car.  The  C-shaped  upper  portion 
13  connected  by  shackles  to  the  elliptical  lower  half,  the  effect  being  to  allow  the 
use  of  fixed  distance  rods  and  keep  the  chain  taut,  without  the  use  of  the  usual 
devices  of  foreign  and  American  carriages. 


FIG.  83a.— Compound  Check-spring  Device  of  the  Mercedes  Car.  The  small  lam- 
inated check-springs  within  the  elliptical  structure  absorb  all  extraordinary  jars 
and  prevent  too  great  distention  under  load. 


Let  S  represent  the  working  span,  or  the  distance  between 
the  centres  of  the  spring  hangers,  when  the  spring  is  loaded. 

Let  W  represent  the  working  strength  of  a  given  spring. 

Let  E  represent  the  elasticity  of  the  spring  in  inches  per  ton. 

The  elasticity  or  deflection  of  a  given  spring  is  found  by  the 
following  formula : 

1.66  =  E  in  1 6th  inch  per  ton  load. 

N  B  T3 


,  RADIUS  RODS  Atib   SHAFTS.  03 

The  span  length  due  to  a  given  elasticity  and  number  and  size 
of  plates  is  as  follows : 

3    

-/  E  B  N  T3    =  S  in  inches. 
V         1.66 

The  number  of  plates  due  to  a  given  elasticity,  span  and  size 
of  plates : 

S3  X  1.66 


EBTs 


N 


The  working  strength,  or  greatest  weight  a  spring  can  bear, 
is  determined  as  follows : 

BTaN 

<r  =  W  in  tons  (2,240  Ibs.)  burden. 

The  span  due  to  a  given  strength  and  number  and  size  of 
plates : 

BT2N 


11.3  W 


S  in  inches. 


The  number  of  plates  due  to  a  given  strength,  span  and  size 
of  plates : 

"*-£*  =  N. 


FIG.  83  -Universal  Jointed  Counter-shaft  of  the  Thornycroft  Steam  Wagon.  This  com- 
persatins  device  differs  from  the  De  Dion,  which  is  on  the  axle.  The  object  is  the 
same,  to  permit  of  an  uninterrupted  drive  under  rise  and  fall  of  springs. 


CHAPTER  EIGHT. 


MOTOR   CARRIAGE   WHEELS. 

Requirements  in  flotor  Carriage  Wheels. —  As  summed  up 
by  a  noted  authority  on  the  subject,  vehicle  wheels  must  have 
three  qualities  of  construction:  (i)  They  must  be  sufficiently 
strong  for  the  load  they  are  to  carry,  and  for  the  kind  of  roads  on 
which  they  are  to  run.  (2)  They  must  be  elastic,  or  so  constructed 
that  the  several  parts — hub,  spokes  and  felloes,  or  rim — are  sus- 
ceptible of  a  certain  flexibility  in  their  fixed  relations ;  thus  neu- 
tralizing much  vibration,  and  allowing  the  vehicle  greater  free- 
dom of  movement,  particularly  on  short  curves  and  when  en- 
countering obstacles.  (3)  They  must,  furthermore,  be  sufficient- 
ly light  to  avoid  absorbing  unnecessary  power  in  moving.  In 
addition  to  these  qualifications,  wheels  suitable  for  automobiles 
must  be  able  to  resist  the  torsion  of  the  motor,  which  always 
tends  to  produce  a  tangential  strain.  This  is  the  reason  why 
tangent  suspended  wire  wheels  are  invariably  used  in  automo- 
biles, instead  of  the  other  variety,  having  radially-arranged 
spokes.  They  must  also  have  sufficient  adhesion  to  drive  ahead 
without  unduly  absorbing  power  in  overcoming  the  tendency  to 
slip  on  an  imperfectly  resistant  road-bed.  The  importance  of  the 
two  last  considerations  may  be  readily  understood  in  view  of  the 
fact  that  the  wheels  of  motor  carriages  receive  the  driving  power 
direct,  instead  of  being  merely  rotating  supports,  like  the  wheels 
of  vehicles  propelled  by  an  outside  tractive  force. 

flethods  of  Constructing  Wheels.  —  In  order  to  meet  the 
conditions  above  mentioned  various  devices  have  been  resorted 
to.  Where  wooden  wheels  are  used  in  any  kind  of  vehicle,  the 
effect  of  elasticity  is  very  greatly  increased  by  "dishing" ;  that  is, 
by  inclining  the  spokes  from  the  exterior  plane  of  the  rim  to  the 
centre  point  of  the  axle  spindle,  so  as  to  make  the  wheel  a  kind  of 
flattened  cone.  This  construction  has  the  effect  of  transforming 
the  spokes  into  so  many  springs,  possessing  elastic  properties, 
and  renders  the  wheel  capable  of  being  deformed  under  sideways 


MOTOR  CARRIAGE  WHEELS.  05 

stress.  The  shocks  of  collision  with  obstacles  are  thus  distributed 
through  the  flexibly  connected  parts,  as  could  not  be  the  case 
if  the  wheel  were  made  in  one  piece  or  on  one  plane,  and  the  con- 
sequent wear  and  strain  is  greatly  reduced.  The  dish  of  the 
wheels  is  usually  balanced  by  slightly  inclining  the  axle  spindle 
from  its  centre  line,  thus  bringing  the  lowest  spoke  to  a  nearly 


FIG.  84.— Wooden  Wheel,  such  as  is  used  on  heavy  gasoline  carriages  of  Panhard,  Hers 
and  others.    It  turns  loose  on  the  axle  and  is  driven  by  a  sprocket  on  a  counter-shaft. 

vertical  position  with  relation  to  the  ground.  A  great  resisting 
power  to  shocks  produced  by  obstacles  such  as  is  afforded  by 
dished  wheels  is  of  far  less  importance  in  vehicles  designed  for 
good  roads,  as  are  most  automobiles,  which  need  only  such  in- 
clination of  the  spokes  as  will  provide  for  the  even  distribution  of 
shocks,  and  the  maintenance  of  uniformity  in  pressure. 

Advantages  Attained  by  Dishing  — The  significance  of  the 
word  "dish"  is  obvious,  when  we  consider  that  it  indicates  a  dia- 
metrical section  of  about  the  shape  of  a  saucer  or  shallow  dish. 
While,  as  we  have  seen,  this  shape  furnishes  a  very  desirable 
spring  effect  against  sidewise  strains  and  shocks,  such  as  are 


96  SELF-PROPELLED    VEHICLES, 

met  in  swinging  around  a  corner  or  sliding  against  a  curb — since, 
although  a  wheel  is  always  weakest  sidewise,  it  is  difficult  to 
thrust  a  cone  inside  out — there  are  several  constructional  con- 
siderations that  render  it  a  desirable  feature  for  wagons  of  all  de- 
scriptions. The  first  of  these  has  reference  to  maintaining  a 
balanced  hang  to  the  wheel.  Under  the  conditions  of  travel 
a  wheel  acquires  the  tendency  to  crowd  on  or  off  the  spindle, 
with  the  result  that  it  eventually  wears  loose,  as  may  be  fre- 
quently found  particularly  on  heavy  carts.  Since  the  spindle  is 
tapered  it  is  necessary  that  its  outer  centre  should  be  lower 
than  the  inner,  and,  then,  in  order  to  counteract  the  outward  in- 
clination of  the  wheel,  and  consequent  tendency  to  roll  out- 
wardly, the  spindle  end  must  be  also  carried  forward  sufficiently 
to  make  the  wheel  "gather,"  which  is  to  say,  follow  the  track. 
A  moderate  dish  contributes  to  the  end  of  bringing  the  tire 
square  to  the  ground,  while  at  the  same  time  enabling  the  wheel 
to  rotate  without  undue  wear  at  the  axle.  Another  constructional 
advantage  involved  in  the  dishing  of  wooden  wheels  relates  to 
the  method  of  shrinking  on  the  iron  tire.  As  is  known,  the  tire  is 
first  forged  to  as  nearly  the  required  diameter  as  possible,  after 
which  it  is  heated,  so  as  to  cause  it  to  enlarge  its  diameter  and 
in  this  state  placed  about  the  rim  of  the  wheel.  When  once  more 
cooled  it  fits  tightly.  As  frequently  happens,  however,  a  tire  is 
made  somewhat  too  small  for  a  wheel,  which  involves  that,  in 
the  act  of  shrinking,  it  will  either  force  the  wheel  into  a  polygonal 
shape  or  crush  one  or  more  of  the  spokes.  By  giving  the  wheel 
a  dish,  the  shrinkage  of  the  tires  merely  increases  the  inclination 
of  the  cone  from  base  to  apex,  the  spring  of  the  spokes  being 
quite  immaterial,  all  suffering  to  about  the  same  extent 

Wooden  Wheels  and  Wire  Wheels. — There  are  two  varieties 
of  construction  used  in  automobiles:  the  one  following  the 
theory  of  the  horse-drawn  vehicle,  with  wrought  frame  and 
wooden  wheels ;  the  other  following  the  construction  of  foot-pro- 
pelled bicycles  and  tricycles,  with  tubular  frame  and  wire  wheels. 
However,  wire  wheels  are  used  on  any  kind  of  vehicle,  and,  fol- 
lowing on  the  practices  of  the  early  makers  of  motor  carriages, 
have  gained  wide  recognition  as  the  typical  construction  for  this 
purpose.  The  principal  argument  for  their  use  is  the  combina- 


MOTOR  CARRIAGE   WHEELS.  97 

tion  of  lightness  and  strength  such  as  no  wooden  wheel  can  attain. 
But  they  lack  elasticity  and  without  pneumatic  tires  are  useless 
for  automobiles.  Indeed,  it  seems  to  be  the  conclusion  of  some 
authorities  that  the  consideration  of  combined  lightness  and 
strength,  urged  alike  for  wire  wheels  and  tubular  frames,  and 
perfectly  proper  in  the  case  of  bicycles,  is  of  the  nature  of  a  super- 
stition, which  is  hostile  to  the  most  advantageous  progress  in 
automobile  construction. 


Fio.  85.— A  Thomas  Motor  Bicycle,  showing  light  tangent-spoke  wire  wheels  and  one 
style  of  mounting  the  motor. 

Relative  flerits  of  Wheels. — In  order  to  briefly  state  the  is- 
sues involved  in  the  case  of  wooden  wheels  against  wire  wheels, 
we  may  say  that  the  main  requirements  in  any  wheel  are,  not  only 
its  ability  to  sustain  a  considerable  weight  in  its  plane,  but  also 
its  power  to  resist  sidewise  strains.  Now,  while  it  is  widely  con- 
ceded that  a  wire  wheel  will  sustain  a  greater  load  than  a  wood 
wheel,  the  two  being  considered  weight  for  weight,  it  certainly 
will  not  sustain  as  great  a  strain  sideways,  which  represents  the 
line  of  the  wheel's  greatest  weakness.  A  wire  wheel  driven  against 
a  curb  with  sufficient  force  will  have  its  rim  dented,  with  the  re- 
sult of  loosening  all  its  spokes  and  ruining  it.  A  wooden  wheel, 
on  the  other  hand,  may  have  a  gap  in  it  and  still  be  serviceable. 
It  may  even  run  with  one  or  several  spokes  broken  off.  A  wire 
wheel  being  suspended  on  its  spokes — the  load  being  hung  be- 


98  SELF-PROPELLED    VEHICLES. 

tween  the  hub  and  the  perimeter — is  bound  to  suffer  in  propor- 
tion to  the  number  of  points  of  suspension  lost.  A  wooden  wheel, 
being  supported  at  both  hub  and  perimeter  by  its  spokes,  has 
a  certain  power  of  compensating  or  distributing  the  strain,  so 
that,  while  a  deficiency  of  support  is  no  advantage,  it  does  not  al- 
ways involve  destruction. 

Disadvantages  of  Light  Construction — On  the  point  of  using 
tubular  frames,  C.  E.  Woods  asserts  that  for  an  electric  cab 
weighing  4,900  pounds  only  200  pounds  is  saved,  while  the  total 
strength  is  no  greater  than  with  wrought  bar  frames  of  suitable 
dimensions.  Moreover,  he  alleges,  that  tubing  is  a  positive  detri- 
ment from  the  fact  that  ordinary  blacksmiths  and  wagonwrights 
cannot  repair  it,  and,  consequently,  that  in  case  of  accident  one 
must  always  resort  to  the  manufacturer.  A  similar  line  of  reason- 
ing is  applicable  to  wire  wheels,  which  involve  the  danger  of 
crystallizing  the  wires  by  unequal  strain  or  adjustment ;  of  crush- 
ing the  rim,  by  running  on  a  deflated  tire ;  or,  of  "buckling"  the 
spokes  by  collision  with  a  curb-stone  or  another  vehicle,  always 
with  the  result  that  others  than  road-side  smiths  must  be  called 
on  for  repairs.  The  sum  of  Mr.  Woods'  argument  is  that  only 
such  constructions  should  be  used  as  may  be  everywhere  readily 
handled  by  skilled  mechanics. 

The  Use  of  Wood  Wheels.— Mr.  Charles  E.  Duryea,  in  a 
letter  to  the  "Horseless  Age/'  argues  ably  for  the  use  of  wooden 
wheels,  with  the  following  statements  of  advantage:  (i)  The 
construction,  proportions  and  strength  suitable  for  given  require- 
ments have  been  carefully  determined  by  years  of  practical  ex- 
perience. (2)  Being  practically  one  piece,  they  do  not  deteriorate 
by  usage  in  bad  weather  and  are  readily  cleaned.  (3)  If  broken, 
they  may  be  anywhere  repaired,  all  the  parts  being  easily  obtain- 
able. (4)  They  will  often  give  good  service  even  in  a  badly 
damaged  condition.  (5)  Experience  has  shown  that  they  are  far 
more  elastic  than  wire  wheels.  (6)  In  wire  wheels  any  attempt  to 
make  the  hub  of  proper  length  to  give  spread  to  the  spokes  under 
strain  results  in  a  clumsy  appearance.  (7)  If  the  spokes  are  pro- 
portionately strengthened  the  wire  wheel  becomes  heavier  than 
the  wood  wheel.  (8)  The  greater  number  of  spokes  in  a  wire 


MOTOR   CARRIAGE    WHEELS. 


99 


wheel,  and  their  proximity  at  the  hub,  where  dirt  and  moisture 
are  collected,  prevents  easy  cleaning  and  promotes  rust.  On 
the  point  of  elasticity  Mr.  Duryea  says :  "As  a  matter  of  fact, 
the  wood  wheel  is  far  more  elastic  than  the  steel  wheel,  as  may  be 
readily  seen  by  watching  a  light  buggy  drive  over  car  tracks  or 
rough  pavements.  The  rims  of  the  wheels  vibrate  sideways, 
sometimes  as  much  as  two  inches,  without  damage  to  the  wheel 
or  axle,  on  which  account  fewer  broken  axles  will  be  had  when 


FIG.  86.— Oldsmobile  Runabout  with  wooden  wheels. 

wood  wheels  are  used  instead  of  wire  ones.  While  it  is  true  that 
the  pneumatic  tire  practically  removes  the  necessity  of  an  elastic 
wheel,  there  is  no  need  of  refusing  to  accept  a  valuable  feature." 
On  the  wagons  manufactured  by  Mr.  Duryea's  company  wooden 
wheels  with  pneumatic  tires  are  used  with  excellent  results.  His 
opinions  on  the  subject  seem  to  be  shared  by  a  goodly  number 
of  motor  carriage  manufacturers,  notably  Haynes-Apperson,  the 
New  York  Electric  Cab  Co.,  and  the  Autocar  Co.,  all  of  whom 
are  now  using  wood  wheels  most  largely,  if  not  exclusively. 

Dimensions  of  Automobile  Wheels. —  The  consideration  of 
wheel  dimensions  is  important  in  automobiles,  and  in  no  other 
particular  is  it  more  essential  that  the  relations  of  size  and  use  be 


100  S&LF-PROPELLED  VEHICLES. 

accurately  calculated.  In  horse-drawn  vehicles  the  forward 
wheels  are  made  of  smaller  diameter,  in  order  to  allow  them  to 
cut  under  the  body  in  turning.  This  consideration  precludes  the 
possibility  of  making  the  diameter  sufficiently  large  to  ensure  all- 
around  easy  running,  except  by  the  use  of  high  frames  or  long 
axle  shafts.  In  automobiles,  on  the  other  hand,  the  forward 
wheels  may  be  of  any  convenient  diameter;  since  by  the  use  of 
knuckle-jointed  steering  axles  a  wide  angle  of  turning  may  be 
obtained  without  using  a  pivoted  axle  shaft.  As  a  general  propo- 
sition we  may  assert  that  the  larger  the  wheel  the  smaller  the 
shocks  experienced  in  passing  over  inequalities  in  the  road  bed, 
and  the  smaller  the  buffing  qualities  required  in  the  tires.  Thus 
it  is  that  a  wheel  five  feet  in  diameter  will  sink  only  one-half  inch 
in  a  rut  one  foot  wide,  while  a  thirty-inch  wheel  will  sink  nearly 
three  times  as  deep,  with  the  result  that  the  resiliency  of  its  tires 
must  be  enormously  larger,  in  order  to  compensate  the  greater 
shock  experienced.  The  larger  wheel  also  rises  less  quickly  over 
obstructions.  These  are  considerations  of  great  importance  in 
motor  vehicles,  in  which  any  device  for  the  reduction  of  vibration 
and  concussion  is  desirable.  Furthermore,  when  a  wheel  is 
properly  tired,  the  road  resistance  to  its  steady  and  even  rotation 
is  decreased  as  the  square  of  the  increase  in  its  diameter,  such  a 
wheel  of  sixty  inches  diameter  decreasing  the  resistance  in  a 
ratio  of  between  50  per  cent,  and  70  per  cent,  as  compared  with  a 
wheel  of  thirty  inches  diameter.  There  are,  however,  other 
methods  for  neutralizing  the  shocks  on  rough  roads.  For,  as 
experience  has  demonstrated,  the  end  of  obtaining  a  low  and 
easy-running  rig  may  be  achieved  quite  as  well  by  increasing  the 
width  of  the  vehicle,  the  length  of  the  springs  and  the  size  of  the 
tires,  as  by  adding  to  the  height  above  the  ground.  By  follow- 
ing this  theory  of  construction,  the  Duryea  Power  Co.  is  able  to 
use  wheels  of  thirty-inch  and  thirty-six-inch  diameter  for  the 
front  and  rear  wheels,  respectively,  and  secure  a  remarkably  easy- 
running  carriage.  They  are  adopting,  however,  a  construction 
which  is,  in  correct  proportions,  very  nearly  equivalent  to  large 
diameter — the  use  of  broad  tires.  For,  as  has  been  repeatedly 
demonstrated,  the  broad  tire  is  superior  to  the  narrow  one  in  the 
very  same  particular,  that  it  will  not  sink  so  quickly  into  mud  and 
sand,  and,  by  its  greater  buffing  properties,  neutralizes  the  con- 


MOTOR   CARRIAGE    WHEELS. 


101 


cussion  otherwise  experienced  with  small  wheels.  Their  thirty- 
eight-inch  springs  are  another  potent  factor  in  achieving  the  de- 
sired end. 

Practical  Points  on  Wheel  Diameter. — While  it  is  no  part  of 
the  province  of  this  book  to  reproduce  the  lengthy  and  elaborate 
calculations  by  which  the  fitness  of  wheels  of  given  diameters, 
breadth  of  tire  and  material  of  construction  is  to  be  determined, 


FIG.  87.— Diagram  showing  the  relative  drop  into  a  road  rut  between  a  small  carriage 
wheel  and  one  twice  its  diameter. 

we  may  briefly  indicate  a  few  of  the  leading  considerations  which 
have  moved  manufacturers  in  general  to  regulate  themselves  on 
these  points.  It  is  a  distinct  advantage  to  enlarge  the  diameter 
of  motor  carriage  wheels  for  the  purposes  of  obtaining  an  offset 
to  the  concussions  experienced  on  rough  roads,  to  obtain  higher 
speed,  within  certain  limits,  and  to  secure  greater  durability  for 
the  tires.  The  last  consideration  is  of  great  importance,  particu- 
larly when  hard  rubber  tires  are  used.  The  principles  involved 
are  well  set  forth  in  a  recent  article  in  the  "Horseless  Age,"  which 
contains  the  following  statements :  "To  prevent  traveling  on  the 
rim  a  tire  should  bind  the  whole  surface  of  the  rim.  The  higher 


102  SELF-PROPELLED    VEHICLES. 

the  wheel  the  more  adhesive  surface  there  is  for  the  tire.  When 
the  tire  is  bound  in  by  lugs  the  natural  kneading  and  straining 
of  it  between  the  lugs  will  in  time  either  shear  off  the  lugs  or 
loosen  them.  Another  reason  why  a  large  wheel  is  to  be  pre- 
ferred from  a  tire-maker's  point  of  view  is  that  a  large  wheel  does 
not  turn  round  so  many  times  in  a  given  distance,  and  conse- 
quently does  not  wear  the  tire  so  fast.  If  a  tire  travels  very  fast 
under  a  heavy  load  the  kneading  of  it  causes  heating  and  crack- 


Fio.  88.— Part  Sectional  View  of  a  Tubular  Steel  Wheel,  used  on  many  automobiles  of  all 
powers.  Although,  to  the  date  of  the  present  writing,  the  principal  issue  among 
authorities  is  upon  the  respective  merits  of  wood  and  wire  wheels,  this  type  of  wheel 
is  steadily  growing  in  favor.  Among  the  advantages  claimed  are:  superior  strength 
to  either  wire  or  wood;  true,  balanced  running,  as  a  pulley  on  a  shaft;  practical  im- 
munity from  dishing  or  crushing  with  the  hardest  use,  or  in  ordinary  accidents;  im- 
munity to  rust,  on  account  of  the  inner  and  outer  brass  coating  on  hubs  and  spokes 
and  the  brazing  at  all  joints;  ability  to  stand  the  twist  and  tension  of  severe  strains 
in  the  transmission  of  power;  rims  formed  from  a  continuous  tube;  spokes  made  from 
high  carbon  cycle  tubing,  oval  in  shape  and  reinforced  at  both  hub  and  rim;  perfect 
alignment  secured  by  assembling  all  parts  in  jigs.  As  shown  in  the  cut,  the  parts  are: 
A,  tubular  steel  rim;  B,  tubular  steel  spokes:  C,  tubular  steel  reinforcement  at  hub; 
D,  tubular  steel  reinforcement  at  rim;  E,  outer  tubular  steel  hub  shell;  F,  middle  tub- 
ular steel  hub  shell;  G,  inner  hub  shell  over  axle  spindle.  The  method  of  securing  the 
hub  to  the  axle  is  also  shown.  Although,  as  must  be  fairly  obvious,  such  a  construc- 
tion admits  of  very  little  sidewise  spring  action  under  stress  of  travel  or  collision, 
which  is  a  particularly  desirable  feature  in  wooden  wheels,  especially  with  steel 
tires,  the  slant  of  the  spokes  effectually  prevents  such  extreme  deformation  as  would 
tend  to  disable  a  wood  or  wire  wheel.  The  oval  shape  of  the  spoke  tubes,  and  their 
arrangement  as  regards  both  hub  and  rim,  enable  the  carrying  of  greater  loads,  in 
proportion  to  weight,  than  are  possible  with  other  varieties  of  wheel.  It  is  also 
possible  to  keep  such  wheels  perfectly  clean,  without  risk  of  injury  by  rust,  as  must 
result  from  attempts  to  wash  wire  wheels,  as  already  stated.  Furthermore,  tubular 
steel  wheels  do  not  shrink  when  dry,  as  do  wooden  wheels,  and,  consequently,  require 
no  process  of  soaking  to  restore  them  to  normal  condition. 

ing,  which  are  intensified  on  the  small  wheel.  Our  experience 
has  proved  that  a  large  wheel  greatly  reduces  the  above  difficul- 
ties." 

Troubles  with  Large  Wheels — As  against  the  above  ad- 
vantages involved  in  the  use  of  large  wheels,  there  are  a  number 
of  objections  of  equal,  if  not  greater,  importance.  Among  these 
may  be  mentioned  the  fact  that,  the  larger  the  wheel,  the  greater 
must  be  its  proportional  strength  and  weight  of  construction,  in 
order  to  neutralize  the  ill  effects  of  torsional  motor  effort,  and 


MOTOR    CARRIAGE    WHEELS. 


103 


£. 

- 

!                                           1 

i 

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B 

a/I 

i     ,/•-—'                                               lx^ 

tl 

FIGS.  89  send  90.— Two  views  of  the  Thornycroft  Spring  Drive  Wheel.    A  is  the  felloe  of 
the  iron  tire.    B  is  the  revolving  axle,  which  is  independent  of  the 


the  wheel  carrying  th — 

wheel  except  for  the  springs  secured  to  it  by  the  bolts,  C. 
the  felloe  carrying  the  lug  to  engage  the  springs,  as  shown. 


D  is  the  angle  piece  at 


104  SELF-PROPELLED    VEHICLES. 

disproportionate  road  resistance.  Indeed,  a  moment's  reflection 
will  show  that  a  wheel  of  sixty-inch  diameter,  built  on  the  same 
dimensions  of  hub,  spokes  and  felloes,  as  a  wheel  of  thirty-inch 
diameter  will  possess  considerably  more  than  twice  the  liability  to 
strain  and  breakage  from  the  causes  above  named.  If  we  may 
assert  that  such  increased  liability,  as  compared  with  the  increase 
of  diameter  is  on  a  ratio  of  three  to  two,  it  is  obvious  that  a  wheel 
of  sixty-inch  diameter  must  be  very  nearly  three  times  as  heavily 
and  strongly  built  as  a  wheel  of  thirty-inch  diameter,  in  order  to 
insure  its  durability.  We  may  readily  judge,  then,  at  about  what 
point  of  increased  diameter  a  light  pleasure  carriage  would  be 
equipped  with  cart  wheels.  This  is  only  one  of  the  numerous 
difficulties  involved  in  attempting  to  use  large  wheels  with  a 
modern  high-speed  motor. 

Thornycroft's  Spring  Drive  Wheel. — A  driving  wheel  much 
like  those  of  the  Hancock  and  Gurney  carriages  is  used  on  the 
steam  road  wagons  manufactured  in  England  and  America,  under 
the  patents  of  John  I.  Thorny  croft.  This  device,  which  is  shown  in 
detail  in  the  accompanying  figures,  consists  of  two  oppositely 
attached  leaf  springs  bolted  rigidly  to  the  end  of  the  rotating  rear 
axle,  and  following  its  motions.  Immediately  in  front  of  these 
springs  is  the  conical  axle  spindle,  and  when  the  wheel  is  set  the 
leaf  springs  engage  lugs  on  the  angle  pieces  bolted  to  the  felloes. 
The  result  is  that  the  motive  power  is  transmitted  solely  through 
the  springs  bearing  on  the  lugs,  which  affords  an  exceedingly 
elastic  connection  on  the  very  circumference  of  the  wheel.  Thus 
reducing  the  motor  strain  to  the  lowest  point,  it  relieves  the 
spokes  of  all  strain  beyond  the  dead  load  carried  on  the  wagon. 
In  the  construction  of  wheels  for  this  purpose,  Thornycroft  fol- 
lows Hancock's  wedge  model,  but  utilizes  the  involved  strength 
and  solidity  far  more  effectively.  Similarly  constructed  wheels 
have  long  been  used  on  the  Huber  traction  engines  with  good 
results,  the  claim  being  that  the  yield  of  the  spring  permits  the 
engine  to  keep  moving  until  the  wheel  is  forced  over  an  obstacle 
in  the  roadway. 


CHAPTER  NINE. 


SOLID   RUBBER  TIRES. 

The  Question  of  Tires.— All  automobiles  and  cycles,  and  a 
large  number  of  horse-drawn  vehicles,  use  rubber  tires.  The 
object  is  twofold:  first,  to  secure  a  desirable  spring  effect; 
second,  to  obtain  the  requisite  adhesion  to  the  road.  While,  with 
properly  constructed  springs,  the  first  result  may  be  achieved 
with  steel  tires,  the  second  is  almost  impracticable  when  the 
power  is  applied  direct  to  the  wheel.  Thus,  if  a  light  automobile 
be  equipped  with  steel  tires,  the  wheels  will  not  drive  on  an  im- 
perfectly resistant  roadbed,  unless  most  of  the  load  be  placed  over 
the  rear  axle,  which,  when  it  is  too  great  in  proportion,  involves 
the  disadvantage,  that  the  steering  will  be  unreliable,  the  forward 
wheels  tending  to  skid,  instead  of  turning  the  vehicle  in  a  positive 
manner.  It  is  not  always  practicable  to  remedy  this  difficulty, 
either  by  strewing  sand  in  front  of  the  wheels  or  by  applying 
power  to  all  of  them.  An  attempt  to  produce  adhesion  by  con- 
structing tires  with  teeth  or  corrugations,  or  by  giving  them 
extra  breadth,  would  increase  the  weight  for  only  temporary  ad- 
vantage. The  simplest  and  readiest  resort  is  found  in  the  use  of 
rubber  tires. 

The  Reduction  of  Vibration. — On  the  point  of  reduced  vibra- 
tion in  a  vehicle,  as  it  is  related  to  the  kind  of  tires  used,  W. 
Worby  Beaumont  says:  "It  must  also  be  remembered  that  the 
greater  comfort  of  the  rider  is  due  to  lessened  severity  of  vibra- 
tion and  shock,  and  this  is  a  relief  in  which  everything  above  the 
tires  participates.  Now,  this  means  a  reduction  in  the  wear  and 
tear  of  every  part  of  the  car  and  motor  which  can  easily  be  under- 
estimated. The  experience  of  the  London  cab-owners,  whose 
records  of  every  cost  are  carefully  kept,  is  a  proof  of  this;  and 
they  find  that  rubber-tired  wheels  suffer  very  much  less  than  the 
iron-tired,  every  part  that  could  be  loosened  or  broken  by  con- 
stant severe  dither  or  hard  vibration  remains  tight  very  much 
longer,  the  breakage  of  lamp  brackets,  hangers  and  other  parts 

105 


106  SELF-PROPELLED    VEHICLES. 

does  not  occur,  and  that  even  the  varnish,  which  being  hard  and 
breakable,  lasts  a  great  deal  longer.  The  same  immunity  of  the 
high-speed  car  is  obtained  by  pneumatics,  as  compared  with 
solids,  and  its  value  is  greater  in  proportion  to  the  greater  value 
of  the  vehicle."  It  may  be  readily  understood  that,  if  such  a 
consideration  is  of  importance  in  horse-drawn  vehicles,  it  is  even 
more  so  in  the  case  of  automobiles,  whose  parts  are  subjected  to 
strain  both  in  traveling  on  rough  roads  and  also  from  the  vibra- 
tion of  their  own  motors.  This  is  particularly  true  of  carriages 
driven  by  gasoline  engines,  in  some  makes  of  which  the  vibration 
is  often  excessive,  generally  increasing  in  direct  ratio  to  the  speed 
at  which  the  carriage  is  propelled.  Hence,  without  some  kind  of 
buffing  properties  at  the  tires,  disaster  must  soon  follow. 

Rubber  Tires  for  Automobiles. — There  are  two  varieties  of 
rubber  tire  in  use  for  every  kind  of  vehicle  except  cycles;  the 
solid  tire  and  the  pneumatic,  or  inflatable  tire.  As  is  generally 
known,  the  pneumatic  tire  was  first  devised  in  order  to  furnish 
the  needed  resiliency  in  bicycles,  and  for  the  same  purpose  it  has 
been  found  useful  in  automobiles,  particularly  in  connection  with 
wire  wheels.  It  has,  however,  one  notable  disadvantage — the 
constant  liability  to  puncture — with  the  consequent  danger  of 
being  made  useless.  In  order  to  remedy  this  defect  inventors 
and  manufacturers  have  introduced  such  features  as  thickening 
the  tread  of  the  tire,  increasing  its  resistance  to  puncture  by  in- 
serting layers  of  tough  fabric  in  the  rubber  walls,  and  even  using 
small  metal  scales. 


Merits  of  Solid  Tires.  —  From  the  standpoint  of  durability 
solid  tires  are  the  best  beyond  question,  not  only  for  heavy  ser- 
vice, but  also  for  high-speed  light  cars.  The  combined  effects  of 
speed  and  weight  work  less  rapidly  upon  them,  enabling  a  greater 
mileage  endurance  than  with  the  best  pneumatics.  Indeed,  it  is 
the  verdict  of  very  many  authorities  that  the  lowest  mileage 
records  have  been  obtained  with  the  use  of  high-priced  pneu- 
matics. Such  tires,  however,  contributing  a  greater  ease  of  travel 
in  most  of  the  ordinary  designs  of  racing  vehicles,  are  used  by 
persons  eminently  well  able  to  afford  the  involved  additional  ex- 


SOLID   RUBBER    TIRES. 


107 


pense.  Consequently,  the  relative  merits  of  the  extremes  are 
quite  immaterial  to  the  general  public.  Commenting  on  the 
statements  of  a  writer  who  contended  that  the  question  of  tires 
suitable  for  various  kinds  of  vehicles  is  largely  an  open  one, 
Mr.  C.  E.  Woods  writes  as  follows :  "The  writer's  own  experi- 


Fig.  92.  Fig.  93. 

FIGS.  91,  92  and  93.— Three  varieties  of  Solid  Rubber  Tire,  showing  shape  and  methods  of 
attaching  on  the  rims.  Fig.  91  shows  a  broad  tire,  which  is  attached  by  forcing  over 
the  edges  of  the  channel-shaped  rim,  to  which  it  is  vulcanized,  and  also  secured  by 
endless  wires,  welded,  as  shown.  Fig.  92  shows  a  tire  secured  by  bolts  through  the 
base,  also  by  annular  lugs  on  the  rim  sides  fitting  into  channels.  Fig.  93  shows  an 
attachment  made  by  connecting  at  the  base  by  a  peripheral  T-piece,  also  by  bolts 
securing  sides  of  channel-shaped  rim.  All  three  varieties  show  rim  channels,  so 
shaped  as  to  allow  of  considerable  distortion,  laterally,  under  load. 

ence  has  been  very  different  in  its  results.  .  .  .  After  the 
construction  of  a  few  vehicles,  early  in  his  development  of  them, 
on  which  he  went  through  the  same  experience  indicated  by  Mr. 
Condict's  article,  he  adopted  the  hard  or  solid  rubber  exclusively, 
and  designed  diameters  of  wheels,  width  of  felloes,  etc.,  to  accom- 
modate such  sizes  of  tires  as  by  experience  proved  best  suited  to 
the  many  and  different  styles  of  vehicles  to  be  built.  For  he  had 
discovered  that  the  resiliency  of  pneumatic  tires  was  entirely  lost 


108 


SELF-PROPELLED    VEHICLES. 


when  the  carriage  was  properly  designed  and  the  weights  proper- 
ly  distributed  on  its  points  of  support,  and  the  latter  placed  on 
properly  designed  springs.  The  easy-riding  carriage  for  any  pur- 
pose depends  entirely  upon  its  springs  for  this  qualification,  and 
there  is  no  reason  why  the  automobile,  with  its  heavier  weight, 
should  be  any  exception  to  the  general  rule.  If,  however,  car- 
riage design  embodies  the  placing  of  a  set  of  batteries  (in 
electric  vehicles)  over  one  set  of  springs,  making  a  very  unequal 
distribution  of  the  load — which  in  itself  is  always  a  faulty  design 
— it  cannot  be  expected  to  be  easy,  and  a  very  large  and  not  too 


FIG.  94.— Indurated  Fabric  Solid  Tire.  This  tire  is  constructed,  so  as  to  prevent  rents  ai  d 
cuts  across  the  tread,  by  inserting  strips  of  tough  fabric  around  the  perimeter,  so 
that  the  edges  are  brought  into  contact  with  the  ground.  Where  clear  rubber  would 
yield,  the  fabric  holds  secure.  The  tire  is  attached  by  bolts  through  the  base,  as 
shown. 

much  inflated  pneumatic  tire  may  help  the  difficulty  a  little.  But 
even  then  when  tires  are  inflated  to  the  pressure  necessary  to  give 
an  economical  power  effect,  there  is  scarcely  any  more  resiliency 
left  in  them  than  that  given  by  a  hard  rubber  tire,  and  their  un- 
sightly and  objectionable  appearance,  as  applied  to  a  general  car- 
riage production,  is  too  well  known  to  need  comment  here." 

Comparative  Values  of  Tires. —  On  the  points  here  made,  Mr. 
Woods  seems  to  have  the  support  of  several  experts  in  the  matter 
of  tires,  although  there  is  a  widespread  agreement  that  pneu- 
matics are  the  only  suitable  ones  for  high-speed,  high-power 
vehicles.  Mr.  Beaumont  writes  as  follows :  "For  high-speed  run- 


SOUS  RUBBER   TtX£S.  109 

fling  with  comfort  over  street  crossings  and  level  railway  cross- 
ings, the  expensive  pneumatic  is  necessary,  but  it  is  a  high  price 
to  pay  for  this  luxury,  and  it  will  only  be  paid  by  the  few  who 
will  pay  anything  for  speed.  After  a  while,  when  automobile 
travel  settles  down  to  the  moderate  speeds  of  the  majority,  and 
to  the  requirements  of  business,  the  better  forms  of  solid  or  near- 
ly solid  tire,  in  which  a  comparatively  small  amount  of  internal 
movement  of  the  rubber  takes  place,  will  probably  be  most  used. 
A  hard  pneumatic  tire  is  superior  to  this  for  ease  at  the  bad  places 
in  roads  and  over  crossings,  but  greater  strength  of  material  suit- 
able for  the  purpose  than  is  yet  available  is  required  to  meet  all 
the  conditions." 


FIG.  95.— Solid  Rubber  "  Sectional  Tire,1'  having  the  tread  divided  into  a  number  of  tooth- 
like  sections,  all  attached  in  one  piece  to  the  rubber  base,  as  shown,  in  order  to  give 
greater  distortion  endwise  under  load,  thus  allowing  of  considerable  cushion  effect. 
It  has  been  claimed  that  the  construction  permits  of  real  resiliency. 

Durability  of  Solid  Tires. — From  the  standpoint  of  lessening 
the  vibration  of  running,  and  thus  preventing  considerable 
damage  to  the  vehicle,  Mr.  Beaumont  concedes  that  pneumatic 
tires  are  preferable,  although,  from  considerations  of  durability, 
he  prefers  the  solids.  As  to  the  life-period  of  solid  tires,  under 
constant  use,  he  says :  "With  regard  to  solid  tires,  the  experience 
of  the  London  hansom  cabs  is  of  much  interest.  A  pair  of  if  or 
if  inch  tires  will  last  from  a  little  over  six  months  to,  at  most, 
nine  months.  The  most  rapid  wear  is  on  those  cabs  which  have 
the  best  and  fastest  horses,  if  we  except  those  cabs  that  have  con- 
stantly to  run  in  districts  where  the  road  surfaces  are  destroyed 
by  the  prevalence  of  tramways,  those  expensive  metallic  admis- 
sions of  the  badness  of  the  ordinary  roads,  and  of  the  incompe- 
tence and  penny-wise  policy  of  most  of  the  road  authorities.  If 


110 


SELF-PROPELLED    VEHICLES. 


thirty  miles  per  day  for  the  hansom  driven  by  men  who  are,  as 
most  are,  allowed  two  horses  per  day,  and  assuming  300  days 
per  year,  then  a  year's  mileage  would  be  9,000.  They  run,  how- 
ever, not  more  than  eight  months  at  best  before  tire  renewal,  so 
that  the  mileage  is  not  probably  more  than  about  5,500  to  6,000. 
.  .  .  The  mileage  of  the  tires  on  the  four-wheel  cabs  is  much 
greater,  as  would  be  expected,  from  the  smaller  weight  each 
wheel  carries  and  the  lower  speed.  The  miles  traveled  per  month 
will  also  be  less." 


FIG.  96.— Wheel  of  the  "  Lifu  "  Steam  Truck,  showing  a  solid  rubber  cushion  tire  secured 
in  position  and  protected  by  metal  shoes  around  the  rim.  Although  the  attachment 
is  so  rigid  as  to  prevent  creeping,  a  very  effective  spring  effect  is  obtained  by  com- 
bination of  the  cushion  tire  and  shoes.  It  is  effective  for  heavy  service,  which  would 
soon  destroy  an  ordinary  solid  tire. 

Structural  Requirements  in  Solid  Tires.— The  shape  and 
methods  of  attaching  solid  tires  to  the  wheel  rims  must  both  be 
determined  with  reference  to  the  source  and  pull  of  the  strains 
likely  to  affect  them.  The  weight  of  the  vehicle  is  nearly  the 
greatest  source  of  wear,  but  even  this  consideration  is  closely 
rivaled  by  the  torsional  strain  from  the  engine  and  in  braking, 
particularly  in  view  of  the  almost  universal  use  of  comparatively 


SOLID   RUBBER    TIRES.  Ill 

small  wheels.  Indeed,  no  part  of  the  wheel  could  suffer  greater 
strain  than  the  tire  from  the  condition  last  mentioned.  In  view  of 
the  properties  of  rubber  it  may  be  readily  seen  that  increasing  the 
thickness  of  the  solid  tire,  in  proportion  to  the  increased  weight 
of  the  vehicle,  will  largely  neutralize  the  destructive  effects  due  to 
every  cause  involved  in  the  structure  of  the  running  gear  and 
its  load.  By  this  means  is  obtained  a  greater  width  of  tread,  with 
a  probably  smaller  total  abrasion  of  the  surface  from  contact  with 
the  road  bed,  and  a  greater  opportunity  for  distributing  and  neu- 
tralizing the  harmful  strains. 

The  tendency  in  solid  tires  is  that  cuts,  due  to  stones  or  other 
sharp  obstacles,  tend  to  spread  to  the  centre  of  the  tire  across  the 
tread.  This  is  due  to  the  quality  of  the  strains  transmitted  from 
the  wheels,  as  above  noted,  and,  in  order  to  prevent  this  tendency 
from  destroying  the  tire  it  is  necessary  to  vary  the  shape.  Ac- 
cordingly, tires  are  made  with  bevel  edges,  rather  than  on  square 
lines,  and  the  profile  is  slightly  rounded.  This  conformation, 
together  with  good  width  at  the  rim,  is  able  to  provide  for  absorb- 
ing much  of  the  surplus  vibration,  while  decreasing  the  ill  effects 
due  to  the  combined  action  of  a  heavy  load  and  road  resistance. 
On  the  whole  it  greatly  prolongs  the  life  of  the  tire.  The  curved 
surface  at  the  tread  and  the  bevel  edges,  tending  to  flatten  under 
the  load,  provide  a  sufficient  width  to  ensure  good  adhesion  and 
the  other  advantages  belonging  to  a  wide  tire,  while,  at  the  same 
time,  reducing  to  "the  minimum  the  tendency  to  spread  tears  and 
cuts,  as  above  mentioned. 

Methods  of  Attaching  Solid  Tires.  —  There  are  several 
methods  of  attaching  solid  tires  to  the  rims,  as  is  shown  by  the 
accompanying  figures.  In  these  typical  structures  the  rim  carries 
flanges  at  either  side  to  retain  the  tire,  or  else  these  flange  pieces 
are  bolted  to  the  felloes.  The  tire  is  also  retained  in  place,  either 
by  a  suitable  shaped  T-piece  running  around  the  circumference 
of  the  rim,  by  wires  drawn  up  to  the  proper  tension  and  electri- 
cally welded  at  the  ends,  or  is  simply  vulcanized  to  the  rim.  The 
last-named  method  of  attachment  is  recommended  by  several 
writers  on  the  subject. 


CHAFER 


THE  USE  AND  EFFECT  OF  PNEUMATIC  TIfcES. 

Advantages  of  Pneumatic  Tires. — As  against  the  opinion  of 
Mr.  Woods,  that  the  solid  tire  is  preferable  for  all  types  and 
weights  of  motor  vehicles,  most  authorities  still  maintain  that  the 
numerous  advantages  gained  in  the  use  of  pneumatics  cannot  be 
dispensed  with  in  automobiles,  nor  obtained  by  the  use  of  any 
other  devices..  One  very  valuable  quality  of  a  pneumatic  tire  is 
its  resiliency,  or  the  ability  to  bounce  in  the  act  of  regaining  its 
normal  shape  after  encountering  an  obstacle  in  the  road.  On 
encountering  such  a  small  obstacle  as  a  stone,  a  pneumatic  tire 
will  yield  to  a  certain  extent,  absorbing  or  "swallowing  it  up,"  at 
the  same  time  exerting  a  pressure  sufficient  to  restore  its  normal 
shape  after  passing  the  obstruction.  This  quality  begets  two 
advantages  for  easy  driving :  It  does  away  with  much  of  the  lift- 
ing up  of  the  wheel  in  passing  over  obstacles,  which  is  otherwise 
inevitable,  and  also  enables  the  tire  to  obtain  a  better  grip  on  the 
road  bed.  Commensurate  advantages  are  also  derived  from  this 
cushioning  quality  in  colliding  with  obstacles  to  one  side  or  other 
of  the  tread;  whence  the  total  pressure  exerted  through  the 
spokes  is  greatly  reduced  and  such  obstructions  exert  only  a 
fraction  of  their  usual  power  to  retard  the  easy  and  steady  opera- 
tion of  the  motor  and  steering  gear.  In  both  cases,  also,  a  large 
part  of  the  shocks  and  vibrations,  usually  transmitted  direct  to  the 
springs,  are  completely  absorbed.  No  solid  tires  could  furnish 
anything  like  such  advantages  in  operation ;  the  usual  result,  even 
with  the  most  flexible  springs,  being  that  the  motor  is  much 
shaken  or  damaged,  or  its  action  largely  impaired.  This  is  par- 
ticularly true  of  the  use  of  solid  tires  on  electric  vehicles,  the 
damage  resulting,  both  in  point  of  efficiency  and  durability,  hav- 
ing been  estimated  by  several  authorities  as  high  as  30  per  cent. 
As  against  this  estimate  we  have  the  above  quoted  experience  of 
Mr.  Woods,  himself  an  expert  and  manufacturer  of  electric 
vehicles.  But  that  it  is  possible  to  supplement  to  a  degree  the 
imperfect  cushion  qualities  of  solid  rubber  tires,  by  the  use  of 

113 


113 

Well-suspended  springs,  seems  to  be  suggested  by  the  report  on 
another  American  make  of  electromobile,  as  published  in  the 
"Horseless  Age."  The  writer  there  states :  "The  springs  used 
on  this  machine  were  extremely  flexible,  so  much  so  that  the 
solid  tires  were  extremely  small,  and  the  writer  understands  that 
the  company  intends  to  use  steel  tires  next  year."  No  data,  how- 
ever, are  accessible  on  the  durability  of  the  motors  used,  nor  on 
the  behavior  of  this  exceptional  machine  on  rough  roadways. 

Speeding  Qualities  of  Pneumatic  Tires. — As  has  been 
already  suggested  by  several  quotations,  the  peculiar  properties 
of  pneumatic  tires  are  nowhere  of  greater  advantage  than  under 
high  speed  conditions.  Since  speed  is  one  of  the  principal  con- 
siderations with  both  builders  and  users  of  automobile  carriages, 
another  source  of  the  pneumatic's  popularity  may  be  recognized. 
On  this  point  the  observations  of  Mr.  J.  W.  Perry,  a  tire  dealer 
of  Paris,  are  significant.  He  says  in  a  letter  to  the  "Horseless 
Age" :  "Automobile  builders,  in  the  course  of  competition  with 
each  other,  have  sought  to  make  or  build  machines  of  great  speed, 
and  each  year  has  brought  us  a  stronger  motor,  with  increased 
speed,  until  we  see  now  motors  of  35  horse-power  that  attain 
speeds  of  90  and  100  kilometers  an  hour  (56  to  62  miles).  No  solid 
tires  could  stand  such  speeds,  and  only  pneumatics  of  the  very 
best  make  can  stand  such  strains.  I  have  made  tests  with  2j 
and  3  inch  solid  rubber  tires  on  automobiles  ranging  from  16 
to  24  horse-power,  and  on  carriages  weighing  I  ton  to  i£  tons. 
After  many  careful  tests,  I  ascertained  that  both  of  these  automo- 
biles could  run  safely  on  a  good  road  at  a  maximum  speed  of 
42  kilometers,  25  i-io  miles,  an  hour.  When  the  driver  at- 
tempted to  go  beyond  this  speed  (always  on  a  perfect  road)  the 
motor  was  subjected  to  such  fearful  vibrations  that  it  threatened 
its  complete  demolition.  Under  the  same  conditions  of  horse- 
power, weights  and  tires,  but  on  what  is  considered  a  bad  road, 
it  was  impossible  to  attain  more  than  15  miles  an  hour.  The 
same  autos,  with  pneumatic  tires  made  60  and  70  miles  an  hour 
on  an  average  road. ' '  While  it  is  perfectly  true  that  the  average 
automobolist  never  contemplates  such  high  speeds  as  Mr.  Perry 
mentions,  it  is  only  fair  to  indicate  that  speed,  combined  with 
general  road  qualities,  merely  furnishes  the  test  conditions  for 


114  SELF-PROPELLED    VEHICLES. 

the  jar-absorbing,  vibration-neutralizing,  and  adhesion-increasing 
properties  of  pneumatic  tires.  Furthermore,  as  the  result  of 
numerous  experiments,  it  may  be  correct  to  assert  that  a  tire, 
best  fitted  to  endure  test  conditions  as  to  speed,  is  also  within 
certain  limits  the  most  suitable  type  and  make  to  travel  under 
heavy  loads,  with  a  minimum  of  traction  effort.  For,  as  most 
figures  seem  to  indicate,  the  decrease  of  traction  effort  is  in  ratio 
with  the  elasticity  of  the  vehicle's  support. 


FIG.  97.— An  electric  ambulance  equipped  with  solid  rubber  tires. 

Economic  Efficiency  of  Pneumatic  Tires. —  In  a  paper  read 
before  the  International  Automobile  Congress  held  in  1900, 
Michelin,  the  well-known  French  tire-maker,  gave  a  number  of 
statistics  relative  to  the  efficiency  of  pneumatics,  as  compared 
with  solid  rubber  and  metal  tires.  His  experiments  are  interest- 
ing as  showing  how  the  efficiency  of  the  pneumatic  tire,  in  point 
of  traction  economy,  increases  directly  as  the  speed  of  the  vehicle. 
Using  an  electric  wagon,  weighing  1,980  pounds,  on  a  level 
Macadam  road,  and  driving  through  a  distance  of  1,000  meters 
in  each  case  under  a  uniform  pressure  of  80  volts,  he  obtained 
the  following  figures  on  traction  effort :  When  running  against 
the  wind,  with  iron  tires,  53.9  amperes;  with  solid  rubber  tires, 


PNEVMATIC  TIRES.  115 

48.5  amperes;  with  pneumatics,  44.2  amperes,  representing  a 
gain  of  10  per  cent,  for  the  solid  rubbers,  and  of  18  per  cent,  for 
the  pneumatics,  as  compared  with  the  iron  tires.  When  running 
with  the  wind,  other  conditions  being  the  same,  the  figures  were : 
With  iron  tires,  50.1  amperes;  with  solid  rubber  tires,  45.2  am- 
peres; with  pneumatics,  41.1  amperes,  representing  a  gain  of  9.8 
per  cent,  for  solids  and  of  18  per  cent,  for  pneumatics,  as  compared 
with  the  iron  tires.  The  average  speed  in  both  cases  was  7.31 
miles  per  hour.  At  a  speed  of  12.31  miles,  he  obtained  a  per- 


FiOv  98  —The  Bailey  Single-Tube  Pneumatic  Tire.  The  tread  is  covered  with  conical  pro- 
jections, which  prevent  slipping,  and  at  the  same  time  promote  traction.  According 
to  the  claims  of  the  manufacturers,  puncture  is  also  made  a  more  remote  possibility. 

centage  of  gain  13  and  28,  respectively,  for  solids  and  pneumatics ; 
the  wind,  however,  being  unfavorable  during  the  test  of  the  iron 
tires.  Nevertheless,  on  a  slightly  muddy  road,  he  registered 
respective  gains  of  10.8  and  20.5,  running  with  the  wind  at  a 
speed  of  12.5 ;  and  on  a  good  road  bed  at  a  4  per  cent,  grade,  1.7 
and  7.8,  for  a  1,210  pound  wagon,  at  6.87  miles.  On  a  5  per  cent, 
grade  covered  with  "sticky  mud,"  the  solid  tires  showed  a  loss  of 
4.7  per  cent.,  and  the  pneumatics  a  gain  of  19.1  per  cent.,  as  com- 
pared with  iron,  at  a  speed  of  11.5  miles;  and  on  the  same  grade, 
with  half-dried  mud,  a  loss  of  7.5  and  a  gain  of  22,  respectively,  at 
a  speed  of  12.5  miles,  the  vehicle  weighing  1,980  pounds  in  both 
cases.  On  the  point  of  such  latter  variations,  Michelin  remarks 
"The  solid  rubber  tire  is  better  than  the  iron  tire  in  certain  cases, 
especially  at  a  trot,  when  the  ground  is  wet,  very  irregular  or 
covered  with  snow;  but  it  becomes  inferior  to  iron  when  the 
road  is  hard  and  smooth ;  in  any  case,  it  never  differs  much  from 


116  SELF-PROPELLED  VEHICLES. 

the  iron  tire,  and  is  always  much  inferior  to  the  phelirriatic. 
pneumatic,  on  the  other  hand,  is  superior  to  the  iron  tire  by  one- 
half."  As  an  average  of  advantage  in  traction,  the  same  authority 
quotes  a  gain  of  18  per  cent,  in  economy  of  energy,  and  5  to  6 
per  cent,  in  speed,  and  by  actual  tests  with  weights,  suspended 
on  a  rope  passed  through  a  pulley  and  attached  to  a  carriage 
having  first,  solid,  then  pneumatic  tires,  he  found  a  weight  of 
508.2  pounds  required  to  start  with  solids,  and  437.8  with  pneu- 
matics. 

Durability  of  Pneumatic  Tires.— In  addition  to  the  apparent 
advantages,  in  point  of  absorbing  jars,  giving  better  adhesion  to 
the  road  surface,  saving  traction  effort,  and  neutralizing  the 
noise  and  vibration  of  motors,  pneumatic  tires,  when  of  sufficient 
proportions  and  properly  attached  to  the  wheels,  are,  all  advan- 
tages considered,  also  the  most  durable.  'That  is  to  say,  when 
calculating  the  superior  speed,  comfort  and  efficiency  made  pos- 
sible by  pneumatics,  we  find  that  their  durability  is  also  greater. 
On  this  point  Michelin  says :  "Metallic  tires  are  quickly  de- 
stroyed by  the  continual  hammering  to  which  they  are  subjected 
on  stone  pavements,  especially  if  the  wheels  carry  a  heavy  load. 
The  metallic  tires  with  which  MM.  De  Dion  and  Bouton  still 
provide  their  heavy  tractors  are  very  quickly  destroyed.  In  a 
very  short  time  the  tires  are  flattened  and  take  the  form  of  a 
trapeze,  the  large  side  of  which  is  in  contact  with  the  ground." 
As  illustrative  of  the  enormous  wear  thus  entailed,  he  quotes  a 
noted  authority  to  the  effect  that  the  tires  of  the  large  transports, 
formerly  used  between  Paris  and  Marseilles,  lost  on  an  average 
of  4  grams  of  metal  per  kilometer,  for  every  1,000  kilograms 
(about  one  ton)  of  freight  load,  giving  for  the  round  trip  "100 
kilograms  (220  pounds)  of  metal  left  in  the  ruts  of  the  road."  M. 
Michelin  quite  properly  exclaims :  "Colossal  figure !"  Yet,  al- 
lowing the  utmost  exaggeration  in  faulty  calculations  or  in 
peculiarly  unfavorable  road  conditions,  we  can  readily  credit  even 
this  statement  on  the  positive  necessity  of  an  elastic  support,  to 
"absorb"  obstacles,  within  reasonable  limits,  rather  than  offer  an 
unyielding,  or  unresilient  surface  for  their  attrition.  Further- 
more, we  may  readily  understand  that  the  average  of  wear,  other 
things  being  always  equal,  must  be  less  when  the  vibrations  are 


PNEUMATIC  TIRES.  117 

absorbed  by  an  air  cushion  than  when  left  to  affect  the  material 
of  a  solid  rubber  tire.  For  ordinary  traffic,  with  moderate 
weights  and  speeds,  the  opinions  of  other  authorities,  as  quoted 
above,  are  competent  in  evidence  for  the  solid,  or  semi-solid,  tire, 
but  practically  all  concede  the  superiority  of  pneumatics  for  the 
uses  enumerated  in  the  various  tests  we  have  mentioned.  It  is 
necessary  to  note  in  this  connection,  however,  that,  despite  the 
enormous  ratio  of  wear  for  steel  tires  on  heavy  motor  vans,  they 
seem  to  be  the  only  possible  support  for  such  use.  Pneumatics 
are  out  of  the  question,  since  they  cannot  be  made  of  combined 
size  and  strength  sufficient  for  heavy  vans,  unless,  as  has  been 


Flo.  99.— The  New  York  B.  &  P.  Single-Tube  Tire.  The  extra  thick  walls  of  this  tire  ren- 
der puncture  less  easy,  and  also  provide  for  a  "  cushion,"  or  semi-solid,  support  in 
case  of  deflation.  The  method  of  attachment  by  lugs  and  nuts  to  a  semi-circular 
channel  is  one  adopted  by  a  large  number  of  other  tires,  affording  a  secure  hold  at 
the  base  to  safeguard  against  creeping. 

suggested,  several  of  them  be  mounted,  side  by  side,  in  parallel 
channels  in  the  rim,,  and  the  solid  rubber  tires  are  only  a  shade 
more  durable. 

Analogies  for  a  Buffing  Support. — In  a  certain  and  very  real 
sense,  the  yielding  tires  of  a  motor  vehicle  supplement  the  action 
of  the  springs,  although  not  permitting  them  to  be  omitted  in 
construction.  In  the  section  on  springs  we  have  seen  that  it  is 
essential  to  correct  theory  and  practice  to  consider  the  vehicle 
and  the  road  it  travels  as  a  working  unity — as  separate,  com- 
ponent parts  of  one  machine.  In  automobile  building  the  prin- 
cipal concern,  in  this  particular,  is  the  vehicle,  which  must  be 
constructed  so  as  to  endure  the  most  unfavorable  conditions  of 


118  SELF-PROPELLED    VEHICLES. 

road  bed.  The  effect  on  the  road  is  quite  secondary.  In  the 
construction  of  railroad  locomotives,  on  the  other  hand,  both 
components  of  the  working  unity,  the  vehicle  and  the  tramway, 
must  be  considered :  both  must  be  constructed  to  interact  with  a 
minimal  wear  and  damage.  In  this  connection  we  may  quote 
Matthias  N.  Forney,  a  well-known  locomotive  expert.  In  speak- 
ing of  springs,  which  in  locomotives  perform  some  of  the  func- 
tions delegated  to  flexible  tires  in  automobiles,  he  says :  "A  light 
blow  with  a  hammer  on  a  pane  of  glass  is  sufficient  to  shatter  it. 
If,  however,  on  a  pane  of  glass  is  laid  some  elastic  substance,  such 


FIG.  100.— The  Michelin  Clincher  Tire.  In  addition  to  the  lugs  and  wing  nuts  which  hold 
the  outer  tube  of  this  tire  to  the  base,  flanges  in  the  length  fit  into  the  grooved  rim, 
making  the  attachment  immovable  when  the  tire  is  inflated. 

as  india-rubber,  and  we  strike  on  that,  the  force  of  the  blow  or  the 
weight  of  the  hammer  must  be  considerably  increased  before 
producing  the  above  named  effect.  If  the  locomotive  boiler  is 
put  in  place  of  the  hammer,  the  springs  in  place  of  the  india-rub- 
ber, and  the  rails  in  place  of  the  glass,  the  comparison  will  agree 
with  the  case  above."  Similarly,  we  may  mention  the  use  by 
printers  of  a  wooden  block  shod  with  leather,  or  any  suitable  sub- 
stance, which,  placed  on  a  form  of  type  and  struck  sharply  with 
a  hammer,  is  efficient  in  producing  a  perfectly  level  printing  sur- 
face. The  same  block,  without  the  yielding  face,  would  un- 
doubtedly batter  the  type  and  injure  the  printing  surface. 
Inversely,  it  is  true  that  the  striking  agent  may  be  worn  and 


PNEUMATIC  TIRES.  119 

damaged — "the  anvil  wears  the  hammers  out,  you  know,"  as  the 
poet  puts  it — hence  the  need  of  a  buffing  medium  to  protect  it 
also.  W'hile  in  automobiles  the  effect  on  the  road  bed  is  incon- 
siderable, the  light  and  delicately-geared  machinery  must  be 
protected  from  damage — the  anvil  must  be  shod.  Whence  it 
follows  that,  in  the  absence  of  anything  like  the  steel  rail  surface 
of  a  railroad,  utility  of  tires  increases  directly  with  their  yielding 
and  shape  restoring  properties.  The  more  readily  these  functions 
are  exercised,  the  smaller  the  wear  on  all  the  elements  composing 
the  working  unity  of  the  machine.  Furthermore,  the  necessity  in 
this  particular  becomes  greater  in  proportion  to  the  weight  and 
contemplated  speed  capacity  of  the  vehicle,  and,  beyond  the  point 
where  pneumatic  tires  are  practical,  must  be  compensated  by 
more  efficient  springs  and  lower  rates  of  travel. 


FIG.  101. -The  G.  &  J.  Tire.  Like  the  Michelin  Tire,  this  is  attached  at  the  base  by  the 
fit  of  the  case  tube  and  rim  channel,  being  securely  held  when  the  tire  is  inflated.  A 
flap  on  the  case  tube  saves  the  inner  tube  from  pinching  at  the  base. 

Structural  Points  in  Pneumatic  Tires.— As  we  have  already 
learned,  it  is  exceedingly  desirable  that  a  pneumatic  tire  should 
be  protected  from  puncture  by  thickening  the  tread,  and  by  some 
such  additional  re-enforcement  as  the  insertion  of  layers  of  tough 
fabric.  These  structural  points  are  embodied  in  several  promi- 
nent makes  of  tire.  But  even  with  such  devices  as  these,  the  tire 
is  not  wholly  protected  from  the  wear  and  strain,  inevitable  in 
driving  under  heavy  load.  Where  pneumatics  are  preferable  to 
solid  tires  it  is  because  of  their  superior  resiliency,  and  because 
of  the  greater  elasticity  of  the  enclosed  air.  It  is  evident,  however, 
that  these  advantages  are  obtained  at  the  expense  of  other  quali- 


120  SELF-PROPELLED    VEHICLES. 

ties,  since  the  pneumatic  tires,  being  much  more  yielding  than  a 
solid,  even  with  the  greatest  compression  of  the  contained  air,  are 
immensely  more  pliable  than  solids.  They  are  thus  liable  to  be 
ruptured  and  rendered  useless  by  an  undue  tangential  pull,  or 
any  such  conditions  as  will  increase  road  resistance  or  promote 
tearing  of  the  sides  or  tread.  Such  conditions  must  be  considered 
in  bicycle  construction,  but  are  vastly  more  important  in  auto- 
mobiles. 

The  situation  as  regards  the  use  of  pneumatic  tires  in  automo- 
biles could  be  no  better  summed  than  in  the  words  of  Mr.  Beau- 
mont. He  says:  "Makers  have  a  problem  of  considerable  im- 


FIG.  102.— The  Dunlop  Double-Tube  Tire.  The  attachment  is  at  the  base  of  the  inner 
tube  by  the  endless  wires  shown,  which  are  pressed  against  the  tubular  sides  of  the 
rim  channel  when  the  tire  is  inflated,  thus  affording  a  positively  immovable  hold. 

portance  before  them  if  they  are  to  respond  to  all  the  require- 
ments of  large  pneumatic  tires  for  considerable  weights.  It  is 
actually  on  the  tread  that  the  obstacle-absorbing  or  deforming 
capability  is  required.  Most  of  the  free  deformation  (under  load) 
must,  therefore,  take  place  elsewhere,  and  this  relegates  the  bend- 
ing to  the  thinner  sides  near  the  rim  and  concentrates  it  there. 
Only  by  adopting  very  high  pressures  and  greater  thickness  of 
textile  material  (at  the  sides)  can  this  be  avoided,  and  this  means 
hard  tires.  Except  for  those  users  to  whom  cost  is  of  no  im- 
portance, this  process  may  go  on  until  the  choice  between  pneu- 


PNEUMATIC  TIRES.  121 

matic  and  solid  or  'compound'  tires  is  a  narrow  one.  It  will, 
however,  always  be  in  favor  of  the  pneumatic  (the  one  of  light 
construction,  as  at  present  largely  used)  where  the  extra  cost  per 
mile  run  is  not  the  first  consideration." 

Construction  of  Pneumatic  Tires.— The  art  of  designing  and 
making  tires  has  advanced  immensely  since  the  first  double  tube 
pneumatics  were  introduced  for  bicycle  use,  about  twelve  years 
since.  The  conditions  attending  their  use  on  all  kinds  of  roads 
have  been  carefully  observed  and  the  dangers  of  rupture  and 
puncture  have  been  reduced  by  proper  constructions  in  a  num- 


Fio.  103.— The  "  Orappler  "  Tire.  Instead  of  endless  wires,  this  tire  carries  projecting 
flanges  of  metal  strips  at  either  side  of  the  base,  which  press  against  the  inner  over- 
lapping  sides  of  the  channel  rim,  affording  a  secure  attachment. 

ber  of  particulars.  As  we  have  already  learned,  such  tires  may  be 
injured  in  three  ways:  (i)  They  may  be  punctured  through  the 
tread  by  collision  with  nails,  glass,  sharp  stones,  or  other  cutting 
obstacles.  (2)  They  may  be  ruptured  at  the  sides,  or  on  the  tread 
when  the  walls  are  made  too  thin,  by  violent  contact  of  any  sort, 
by  the  torsional  strain  produced  by  the  motor,  or  when  the  brake 
is  suddenly  applied.  (3)  They  may  be  cut  or  worn  at  points  of 
jointure  to  the  rims,  when  sufficient  precautions  are  not  taken. 
Other  such  sources  of  disablement,  besides  steady  wear  might  be 
enumerated,  but  these  categories  include  most  of  the  familiar 
occasions  of  accident.  Accordingly,  we  find  that  manufacturers 
have  busied  themselves  in  devising  and  producing  means  for  pro- 
tecting pneumatic  tires  at  the  points  most  liable  to  damage,  (i) 
The  tread  is  made  of  extra  thickness  of  rubber,  and  further  rein- 


122  SELF-PROPELLED   VEHICLES. 

forced  by  enclosed  layers  of  textile  material,  which  is  particularly 
efficient  protection  when  inserted  as  strips  cut  bias.  (2)  The 
side  walls  are  similarly  thickened  and  reinforced.  (3)  The  points 
of  contact  and  jointure  are  protected  with  thread  or  woven  fabric. 

Causes  of  Puncture. — According  to  the  experience  of  several 
tire  experts,  the  devices  ordinarily  employed  to  protect  the  tread 
of  tires  are  largely  useless  from  the  fact  that  they  very  often 
involve  other  causes  of  breakage  in  themselves,  thus  enabling 
the  verdict  that  by  far  the  smaller  proportion  of  tire  disablements 


FIG.  104.— The  Goodyear  Double-Tube  Tire.  The  attachment  of  this  tire  is  by  the  strips 
of  wire,  woven  like  a  cotton  shoestring,  which  spread  apart  under  the  pressure  of  in- 
flation, thus  securing  a  rigid  hold. 

is  due  to  puncture.  By  reinforcing  the  tread  beyond  a  certain 
definite  point  we  contrive  to  shorten  the  tire's  life  on  account  of 
the  more  difficult  bending  of  the  walls,  occasioning  sharp 
corners  and  consequent  rupture  of  the  fabric.  Like  several  other 
causes  of  disablement,  puncture  may  be  said  to  result  most  often 
from  the  use  of  insufficient  diameter  in  the  tires,  rather  than 
from  walls  too  thin  or  yielding.  Indeed,  it  seems  to  be  a  well- 
ascertained  fact  that,  other  things  being  equal,  a  tire  of  propor- 
tions suited  to  the  vehicle  will  resist  puncture,  while  one  of 


PNEUMA  TIC  TIRES. 


123 


smaller  diameter  will  be  cut  with  very  much  greater  ease.  The 
larger  sizes  of  pneumatics,  such  as  the  four  and  five-inch,  owe 
their  short-lived  usefulness  to  other  causes,  yet,  Mr.  Beaumont, 
to  the  contrary  notwithstanding,  pneumatic  tires  of  four  inches 
diameter  are  more  durable  by  half  than  the  continuous  solid 
rubber  suited  to  the  same  size  and  weight  of  vehicles,  the  former 
representing  an  average  total  mileage  of  3,000  to  the  latter's 
1,500,  as  result  of  a  number  of  tests  with  heavy  high-speed  vehi- 
cles. In  this  connection  it  is  well  to  remark  that  Mr.  Beau- 
mont's statements  are  accompanied  by  no  figures  or  reports  of 
tests,  which  make  it  probable  that  they  are  based  on  simple 


Fio.  105.— The  Munger  Single-Tube  Tire.  This  view  shows  the  tire  deflated,  so  that  the 
longitudinal  rubber  buffers  come  together,  thus  forming  a  semi-solid,  or  cushion  tire, 
and  preventing  the  inconvenient  consequences  generally  following  this  condition. 

calculations  gained  from  experience  with  vehicles  of  moderate 
size  in  regard  to  which  they  may  hold  good  within  limitations. 
The  pneumatic  tires  suited  to  bear  the  weight  of  heavy  vehicles 
are  deficient  in  durability  on  account  of  their  large  proportions 
— none  can  be  made  larger  than  five-inch  diameter — thus  no 
statistics  are  trustworthy  which  are  based  on  the  behavior  of 
such  large  pneumatics,  as  compared  with  solid  tires  fitted  to 
smaller  vehicles.  Solid  tires  made  of  size  sufficient  for  the  pur- 
poses of  large  racers,  unless  in  some  way  strengthened  length- 
wise the  tread,  as  are  the  indurated  fabric  tires  recently  intro- 
duced, would  quickly  tear  across  and  become  useless.  Heavy 
vehicles  are,  therefore,  often  equipped  with  sectional  solid 


124:  SELF-PROPELLED    VEHICLES. 

rubber  tires,  as  they  are  called,  consisting  of  a  continuous  rub- 
ber band  bearing  a  number  of  tooth-like  sectional  pieces,  pro- 
jecting from  the  circumference.  Some  manufacturers  of  such 
tires  claim  a  good  degree  of  resiliency  for  them,  alleging  this 
style  to  be  ''the  only  tire  which  has  withstood  the  tremendous 
wear  and  tear  of  heavy  automobile  use  for  a  satisfactory  length 
of  time." 

Constructional  Requirements  in  Single  Tube  Tires — In  an 

article  contributed  to  the  "Horseless  Age,"  Pardon  W.  Tilling- 
hast,  the  inventor  of  the  original  single-tube  pneumatic  tire, 
writes  as  follows  regarding  the  structural  requirements  of  single- 
tube  tires  for  automobiles : 

"To  accomplish  the  best  results  and  manufacture  a  tire  that 
will  be  practically  indestructible,  a  fabric  must  be  employed  in 


FIG.  106.— The  Ball  Tire.  In  this  tire  the  ill  effects  of  puncture  are  prevented  by  the  solid 
rubber  balls  inserted  in  the  tube,  which  transform  the  tire  into  a  cushion,  positively 
proof  against  flattening. 

which  there  is  no  starting  point  of  separation  between  the  fabric 
and  rubber,  and  one  that  does  not  have  a  substantially  smooth 
surface,  or  a  surface  that  is  continuous  in  the  same  plane.  The 
attaching  surface  of  the  fabric  presented  for  union  with  the  rub- 
ber must  be  greatly  in  excess  of  that  furnished  by  the  fabrics  in 
use  at  the  present  time.  A  plurality  of  plies  may  be  used,  some 
of  the  plies  having  a  more  open  weave  or  construction  than  other 
plies,  and  all  plies  separated  by  rubber,  which  will  give  in  effect 
a  single  tube  or  mass  of  rubber,  having  fibrous  threads  extend- 
ing throughout  the  mass  to  prevent  bursting,  and  binding  the 
whole  structure  into  a  substantially  indestructible  body.  . 

"Another  means  of  accomplishing  the  same  end  consists  es- 
sentially of  employing  a  fabric  which,  when  built  into  a  tire,  will 
have  the  same  effect  that  a  bath  towel  would  if  it  was  inclosed 


PNEUMATIC  TIRES. 


125 


and  imbedded  in  the  rubber,  with  the  threads  sufficiently  strong 
to  withstand  the  inclosed  air  pressure,  the  little  loops  or  fibres 
extending  away  from  the  general  plane  of  the  main  fabric  into 
the  surrounding  rubber  and  being  vulcanized  therein,  furnishing 
an  increased  surface  for  union  with  the  rubber;  the  general  sur- 
face line  of  the  fabric  in  each  construction  is  to  be  broken  so 
that  it  is  not  continuous  in  the  same  plane,  and  there  is  no  start- 
ing point  of  separation  between  the  fabric  and  rubber." 

Two  recent  patents  granted  to  Tillinghast  cover  devices  for 
achieving  the  ends  here  mentioned.     One  of  these  tires  is  built 


FIQ.  107.— The  construction  of  the  new  types  of  Tillinghast  Single-Tube  Tires, 
shows  the  formation  of  the  fabric  into  a  succession  of  loops;  the  second, 
thread  fabric  tire. 


The  first 
the  open 


up  with  a  number  of  strands  of  thread  running  longitudinally 
on  the  tube  and  wound  spirally  with  other  threads  which  hold 
them  securely  under  inflation.  The  spiral  windings  are  then 
pushed  along  the  length  of  the  tube,  so  as  to  reduce  the  distance 
between  the  windings  from  one-quarter  inch  to  less  than  one- 
eighth  inch,  with  the  result  that  the  intermediate  sections  of  the 
longitudinal  threads  are  pushed  up  into  series  of  loops,  thus 
forming  stronger  attachments  for  the  fabric,  when  held  in  the 
material  of  the  rubber  wall  built  up  over  this  layer  of  threads. 
Tillinghast's  other  patent  covers  a  method  of  strengthening  the 


126 


SELF-PROPELLED    VEHICLES. 


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llff^-lltljfjlfl 


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PNE  UMA  TIC  TIRES.  1 2  7 

fabric  against  any  cause  that  would  tend  to  bursting  or  tearing 
the  walls,  and  specifies  a  series  of  plies  or  layers  of  threads  wound 
on  in  two  diagonal  directions,  each  one  being  in  a  more  open 
construction  than  the  last,  the  closest  construction  being  on 
the  inmost  ply  of  the  tire. 

Attaching  Single-Tube  Pneumatic  Tires — The  typical 
method  of  attaching  a  pneumatic  tire  to  the  wheel  is  that  made 
familiar  in  bicycles.  Where  a  wood  rim  is  used  the  process  is, 
briefly,  to  thoroughly  clean  the  surfaces  of  both  tire  and  rim,  after 
which  two  successive  coats  of  shellac  varnish  are  applied  to  both 
and  allowed  to  dry.  This  varnish  is  made  by  dissolving  two 
pounds  of  gum-shellac  in  one-half  gallon  of  alcohol.  Another 
method  of  preparing  rubber  cements  for  similar  purposes  is  to 
dissolve  shellac  in  ammonia.  The  practice  with  ordinary  shellac 
varnish  is  to  apply  and  let  dry  two  successive  coats,  after  which  a 
third  coat  is  given  to  both  tire  and  rim  and  the  tire  is  attached, 
valve  first,  and  secured  in  position  by  a  good  degree  of  inflation. 
The  varnish  is  thus  able  to  increase  the  tire's  adhesion  to  the  rim 
so  long  as  it  remains  inflated.  Thus  the  inflation  of  the  tire  is  an 
essential  element  to  the  end  of  retaining  its  hold  on  the  rim ;  for 
the  coating  of  shellac  would  speedily  tend  to  lose  its  grip  if  the 
inflation  becomes  sufficiently  imperfect.  As  the  result  of  in- 
sufficient inflation,  among  other  causes,  there  are  two  familiar 
occasions  of  accident :  The  tire  will  "creep,"  or  move  longitud- 
inally upon  the  periphery  of  the  rim ;  or  it  will  "roll"  off  the  edge 
sideways. 

The  Creeping  of  Tires.— The  creeping  of  a  tire  is  due  to  the 
fact  that  the  weight  of  the  vehicle,  in  process  of  travel,  tends  to 
centralize  the  pressure  on  the  rubber  walls,  and  cause  the  tire  to 
bulge  just  forward  of  the  point  of  contact  with  the  ground.  As 
may  be  readily  recognized,  a  continued  succession  of  such  bulg- 
ings  tends  both  to  loosen  the  adhesion  of  the  tire  and  the  rim, 
and  also  to  cause  the  tire  to  push  forward  from  the  ground,  and 
thus  around  the  rim,  in  the  effort  to  relieve  and  distribute  the 
pressure.  As  a  result,  when  inflation  is  insufficient,  great  strain 
and  pull  will  be  exerted  where  the  valve  is  joined  to  the  tire,  and 
a  rupture  often  follows  at  that  point.  Even  were  it  possible  to 


128 


SELF-PROPELLED  VEHICLES. 


obviate  the  last-named  accident,  it  is  evident  that  the  service  of 
a  tire,  thus  loosened  by  the  creeping  process  is  impaired.  More- 
over, it  would  inevitably  roll  sideways  from  the  rim  before  it  had 
been  long  in  use.  Also,  if  loose,  it  chafes  at  the  rim  and  wears 
quickly. 

Attachments  That    Prevent    Creeping.— It  seems  to  be  a 
well-established  conclusion  that  a  single-tube  pneumatic  is  more 


FIG.  109.— Showing  the  method  of  removing  the  case  tube  of  a  Dunlop  tire.  Two  tools, 
like  that  shown  at  top  of  the  figure,  are  inserted  between  the  rim  channel  wall  and 
the  tire,  as  at  A,  after  deflation.  The  edge  of  the  tube,  being  pushed  into  the  central 
channel,  is  then  raised,  as  at  B.  When  one  wire  ring  has  been  raised  above  the  edge 
of  the  channel,  the  case  tube  is  worked  off,  as  shown.  (See  Fig.  103.) 

liable  to  creep  than  one  of  the  double  tube  variety.  However, 
this  may  be  in  some  measure  owing  to  the  fact  that  the  structure 
of  double  tube  tires  more  readily  permits  the  use  of  devices  for 
promoting  rigidity  at  the  base,  and  that  the  majority  of  them  are 
equipped  with  such  devices.  Perhaps  the  simplest  attachment  of 
the  kind  is  that  shown  in  the  figure  of  the  New  York  Belting  and 


PNEUMA  TIC  TIRES. 


129 


Packing  Co.'s  heavy  single  tube  tire.  A  series  of  chaplet  heads 
carrying  lugs  are  inserted  in  the  layers  of  fabric,  and  these  lugs, 
being  passed  through  holes  drilled  in  the  rim,  are  secured  in  place 
by  screws  and  washers.  Given  strong  layers  of  fabric,  as  is 
always  essential  to  the  success  of  this  construction,  it  is  evident 
that  the  tire  will  have  a  very  rigid  attachment  to  the  rim  at  the 
base,  by  which  the  evil  effects  of  creeping  will  be  reduced  to  the 
lowest  point,  if  the  tendency  is  not  practically  obviated.  It  has 
been  widely  used  with  both  varieties  of  pneumatic  tires,  its  suc- 
cess with  double  tubes  having  been  particularly  good  in  con- 
nection with  the  Michelin  clincher  and  others  of  similar  pattern. 


FIG.  110.— Method  of  repairing  a  single  tube  tire.  In  case  of  puncture,  mushroom  patches, 
as  at  A,  are  inserted  in  the  hole,  which  is  usually  enlarged  with  a  red  hot  wire 
Liquid  cement  is  then  injected,  as  at  B,  from  a  specially  prepared  syringe,  furnished 
with  all  repairing  outfits.  The  patch,  also  cemented,  is  then  inserted  as  at  C 
position  in  the  tube  is  shown  at  D  ;  where  it  is  pulled  into  shape  by  the  thread 
tied  to  its  stem  and  held  by  the  pressure  of  inflation.  When  the  tire  is  inflated  hard 
the  patch  stem  is  cut  off,  and  the  tube  and  rim  are  wrapped  about  with  moist 
cemented  tape,  as  at  D  in  Fig.  111. 

Care  and  Repair  of  Pneumatic  Tires.— As  we  have  already 
seen,  there  are  two  varieties  of  pneumatic  tire,  designated  re- 
spectively as  the  "single-tube"  and  the  "double-tube."  The  latter 
was  invented  and  introduced  by  an  Englishman,  Dunlop,  now  so 
widely  known  for  his  work  in  this  field,  about  1888;  the  former, 
by  Pardon  W.  Tillinghast,  of  Providence,  R.  I.,  about  two  years 
la'ter.  The  immense  impetus  immediately  given  to  the  bicycle  in- 
dustry by  the  successful  production  of  an  inflatable  support  is 
historic.  Previous  to  this  period  some  bicycles  manufactured  by 


180 


SELF-PROPELLED   VEHICLES, 


the  Overmans,  of  Springfield,  Mass.,  had  been  equipped  with  a 
"cushion  tire,"  which  was  an  arch  of  heavy  rubber  attached 
by  its  feet.  It  was  an  improvement  in  many  respects  on 
the  solid  rubber  tires,  until  then  in  universal  use,  but  afforded,  at 
best,  a  very  poor  imitation  of  resilient  wheel  support.  Such  a  tire, 
of  course,  required  no  inflating,  and  was  not  injured  by  simple 
punctures  in  its  tread.  Hence  it  involved  no  troublesome  processes 
of  repair,  whenever  disabled.  Pneumatics,  on  the  other  hand,  are 
entirely  disabled  by  puncture,  although,  unless  of  an  unusually 
serious  nature,  such  injuries  may  be  repaired  on  the  road.  In 


FIG.  111.— Showing  method  of  repairing  small  punctures.  Instead  of  mushroom  patches, 
ordinary  rubber  elastic  bands  are  strung  on  the  kind  of  tool  shown  at  A,  as  at  B. 
Rubber  cement  is  then  injected  into  the  tube  of  the  tire  through  the  puncture,  and 
also  smeared  on  the  rubber  bands,  held  as  at  B.  The  tool  carrying  the  bands  is  then 
inserted  in  the  puncture,  as  at  C;  the  protruding  ends  of  the  rubber  bands  are 
pared  off,  and  the  tire  tube  is  wrapped  with  cemented  tape,  as  shown  at  D. 

point  of  ease  of  repair,  the  single  tube  pneumatic  is  preferable, 
and  this  was  one  of  the  considerations  which  led  to  its  almost 
universal  adoption  for  bicycles,  instead  of  the  double  tubes  first 
used.  The  double  tubes,  however,  possess  so  many  advantages  in 
other  directions,  some  of  which  we  have  already  learned,  that  the 
last-named  consideration  is  quite  counterbalanced  in  the  calcula- 
tions of  automobile  manufacturers.  In  both  varieties  of  tire  the 
outer  layers  of  rubber,  which  are  alternated  with  layers  of  fabric, 
are  of  a  quality  best  calculated  to  resist  wear,  and,  with  the 
enclosed  fabric,  present  a  tough,  though  elastic,  surface  to  the 
ground.  The  air  tubes  in  both  are  of  pure  rubber,  of  practically 


PNEUMATIC 


181 


no  strength,  but  of  the  greatest  efficiency  in  retaining  air.  Thus, 
when  the  tire  is  inflated,  the  air  is  retained  by  the  inside  rubber 
tube  and  prevented  from  leaking  through  the  interstices  in  the 
rubber  and  fabric  layers  surrounding  it.  The  single-tube  tire 
differs  from  the  double-tube  in  the  fact  that  the  inner,  or  air, 
tube  is  vulcanized  to  the  outer,  or  cover,  tube;  while,  in  the 
double-tube  variety  they  are  separately  attached  to  the  wheel  rim, 
and  should  not  be  in  contact  except  under  inflation.  As  may  be 
understood  on  reflection,  a  puncture  through  the  tread  of  a 
single-tube  tire  may  be  readily  repaired  by  the  use  of  mushroom- 


FIG.  112.— The  "Kelly"  Tire  Repairing  Tool.  This  instrument  consists  of  a  hollow  and 
slotted  awl,  made  to  slide  within  a  cylindrical  sleeve  having  a  bell-shaped  end.  In 
case  of  puncture  rubber  cement  may  be  forced  into  the  tire  through  the  hollow  awl. 
Several  rubber  bands,  generally  six,  are  then  attached  to  the  instrument,  as  shown; 
one  end  of  each  being  inserted  in  the  slotted  point  of  the  awl,  the  other  ends  being 
hung  on  the  pins  projecting  at  the  sides  of  the  sleeve.  The  needle  is  then  forced  in 
fully,  the  sleeve  being  still  held  away  from  the  surface  of  the  tire.  Then  the  bell- 
shaped  end  of  the  sleeve  is  set  against  the  tire,  enabling  the  needle  to  be  withdrawn, 
leaving  one  end  of  each  band  projecting  inward  through  the  puncture,  the  other  end 
being  loosened  from  the  pins.  The  ends  of  the  bands  may  then  be  pared  off,  leaving 
the  surface  smooth. 

FIG.  112a.— The  "  Sennevoye  "  Repairing  Strap.  In  addition  to  the  patches  for  covering 
punctures  on  the  inner  tube,  this  strap  is  buckled  around,  as  shown,  to  further  close 
and  protect  the  injured  point. 

shaped  rubber  patches,  which  are  carefully  inserted  in  the  hole 
and  secured  in  place  with  cement  under  the  pressure  of  inflation. 
With  the  double-tube  tire,  on  the  other  hand,  the  casing  tube 
must  be  removed  from  the  inner,  upon  which  suitably-sized 
patches  are  then  cemented,  or  still  more  elaborate  repairs  made, 
according  to  the  gravity  of  the  accident.  In  cases  of  emergency, 
as  when  a  puncture  occurs  on  the  road,  the  double-tube  tire  may 
be  repaired  in  the  same  manner  as  the  single-tube,  thus  involving 


182  SELF-PROPELLED   VEHICLES. 

that  the  tubes  be  cemented  together,  but  the  repair  man  can 
readily  cut  the  adhesion  with  benzine  or  gasoline  and  make  th^ 
necessary  repairs  in  the  proper  fashion.  With  a  single  tube  tire 
the  patch  is  put  on  the  inside  of  the  air  tube,  as  shown  in  the 
figures,  being  held  in  place,  until  the  cement  sets  by  the  pressure 
of  the  contained  air.  But  in  case  of  puncture  in  an  inner  tube  of 
a  double-tube  tire,  a  patch  of  cemented  rubber  or  other  adhesive 
is  generally  attached  on  the  outside  of  the  air  tube.  The  adhesion 
is  then  maintained,  until  the  cement  has  set,  by  the  pressure  of 
the  air  tube  against  the  case  tube.  In  order  to  afford  protection 
to  this  patch,  rubber  bands  have  been  recently  introduced  which 
buckle  around  the  injured  section  and  retain  the  patch  under  in- 
flation. This  operation  of  patching  an  inner  tube  may  be  per- 
formed by  the  roadside  by  an  experienced  hand,  when,  as  fre- 
quently happens,  necessity  so  demands. 

Proportions  of  Pneumatic  Tires.— Very  nearly  the  most  im- 
portant consideration  in  point  of  securing  durability  and  long 
service  in  a  pneumatic  tire  is  that  it  should  be  of  dimensions  suited 
to  the  vehicle  it  must  support.  Many  accidents  and  other  disable- 
ments have  arisen  from  the  habit  of  using  tires  too  small  for  the 
load.  On  the  other  hand,  no  particular  advantage  can  come  from 
using  tires  that  are  too  large.  The  dimensional  limits  for  practical 
pneumatic  tires  are  between  diameters  of  ij  and  5  inches,  but 
the  service  requirements  of  most  automobile  carriages  fall  far 
within  these  figures.  As  given  -by  a  well-known  tire-manufactur- 
ing firm,  the  following  figures  represent  about  the  correct  pro- 
portions for  single-tube  tires : 

For  static  load  up  to  250  pounds,  use  a  tire  of  if -inch  outside 
diameter. 

For  static  load  between  250  and  400  pounds,  use  tires  of  2-inch 
outside  diameter. 

For  static  load  between  400  and  600  pounds,  use  tires  of  2j-inch 
outside  diameter. 

For  static  load  between  600  and  1,200  pounds,  use  tires  of 
3-inch  outside  diameter. 

For  static  load  between  1,200  and  2,500  pounds,  use  tires  of 
4-inch  outside  diameter. 


PNEUMATIC  TIRES. 


133 


For  static  load  between  2,500  and  5,000  pounds,  use  tires  of 
5-inch  outside  diameter. 

For  double-tube  tires  the  same  figures  apply  approximately. 
The  manufacturer  of  the  G.  &  J.  tires  gives'the  following  figures : 

For  a  static  load  of  600  pounds  or  less,  use  tires  of  2|-irich 
diameter  on  case  tube. 

For  static  load  of  600  to  900  pounds,  use  tires  of  2\  or  3  inch 
case  tube  diameter. 

For  static  load  of  900  to  1,200  pounds,  use  tires  of  3-inch  case 
tube  diameter. 


FIG.  118. — A  De  Dion  Gasoline  Quadricycle,  for  carrying  two  persons.  This  vehicle  con- 
sists of  a  motor  tricycle  whose  forward  wheel  has  been  removed  in  order  to  allow 
attachment  to  the  two-wheeled  fore-carriage,  as  shown. 

Although  these  figures  seem  to  indicate  that  double-tube  tires 
of  somewhat  smaller  diameter  may  be  safely  used,  it  is  quite  cer- 
tain that  the  estimates  are  rather  general  than  specific,  and  that 
the  question  of  proper  tires  for  each  particular  vehicle  is  settled 
with  reference  to  the  extreme  wheel  diameter  and  other  propor- 
tions. For  a  motor  carriage  demands  not  only  an  elastic  sup- 
port, but  also  one  of  sufficient  contact  surface  to  enable  its  resili- 
ency and  adhesion  to  be  efficient  under  load  and  at  good  speeds. 
Thus,  while  it  is  desirable  to  strengthen  the  rubber  and  fabric 


134  SELF-PROPELLED   VEHICLES. 

walls  as  much  as  possible  against  puncture  and  all  undue  wear 
and  tear,  it  is  even  more  important  that  the  cubic  content  of  the 
air  chamber  should  be  of  a  proportionate  size  to  give  commen- 
surately  good  results.' 

The  Effects  of  Resiliency  in  Tires — A  practical  test  of  re- 
siliency may  be  made  by  lifting  a  bicycle  or  vehicle  wheel,  bearing 
an  inflated  tire,  and  allowing  it  to  fall  a  foot  or  so  to  the  ground. 
The  result  will  be  that  the  entire  structure  will  rebound  a  con- 
siderable number  of  times  before  falling  flat,  which  fact  shows 
how  efficient  a  spring  device  is  interposed  between  the  vehicle 
and  the  road  surface;  also,  how  great  a  capacity  for  absorbing 
small  jars  is  employed  in  addition  to  the  springs.  If,  now,  a 
wheel  shod  with  a  solid  rubber  tire  be  allowed  to  fall  to  the 
ground  in  similar  fashion,  very  little,  if  any,  rebound  will  be 
observed,  which  goes  to  show  that  the  solid  tire  possesses  no 
capacity  whatever  for  supplementing  the  springs  in  the  absorption 
of  jars ;  it  throws  all  of  this  work  upon  the  springs,  which  must, 
in  consequence,  be  exceedingly  well  calculated,  in  order  to  pre- 
vent excessive  vibration  and  rocking  of  the  carriage  body.  This 
is  the  reason,  as  already  stated,  that  it  is  impossible  to  attain 
high  speeds  on  ordinary  roads  without  the  use  of  pneumatic 
tires.  The  roads  in  such  cases  need  to  be  smoothed  in  some 
manner,  and,  as  must  be  obvious  on  reflection,  this  function 
does  not  properly  belong  to  the  wagon  springs  and  cannot  be 
delegated  to  them  without  considerable  inconvenience.  In  a 
few  words,  the  case  of  the  motor  carriage  is  precisely  similar 
to  that  of  the  railroad  car,  which  has  the  rails  of  the  track  to 
render  possible  the  desired  ends  of  perfect  traction  and  high 
speed,  with  the  minimum  of  jar  and  vibration;  it  has  a  ready 
smoothed  road  to  run  on.  The  motor  carriage  cannot  have  such 
a  track,  hence  must  make  its  own  smooth  and  even  traction 
surface,  as  it  moves  along. 

Testing  Pneumatic  Tires — As  seems  reasonable  on  reflec- 
tion, there  is  a  vast  difference  in  point  of  resiliency  between  the 
various  makes  and  grades  of  pneumatic  tires ;  also  between 
tires  of  different  sizes,  and  between  single-tube  and  double-tube 
tires.  Usually  the  diameter  of  the  tire  to  be  used  is  calculated 
with  reference  to  the  weight  of  the  vehicle,  the  idea  being  that  a 


PNEUMATIC  TIRES.  135 

given  diameter  of  tube  will  yield  a  certain  proportionate  resilient 
effect  and  tractive  efficiency.  There  is,  however,  a  very  close 
connection  between  the  two  properties,  since  a  tire  whose  reac- 
tive quality  is  high  is  superior  for  traction  to  one  that  is  more 
rigid.  This  is  true  because  greater  compressibility  entails  a 
broader  surface  to  bear  upon  the  road,  while  a  greater  reactive 
power  in  a  tire  in  resuming  its  proper  shape  after  deformation 
under  load,  or  from  contact  with  obstacles,  requires  a  smaller 
traction  effort  to  ensure  forward  progress.  Hence,  to  determine 
the  serviceability  of  a  tire  the  question  of  its  resiliency  as  com- 
pared with  others  is  very  nearly  paramount. 

Duryea's  Tests  for  Resiliency — Very  few  statistics  on  this 
subject  have  been  published  up  to  the  present  time,  and  very  few 


Fio.  114.— Diagram  showing  test  of  resiliency  of  a  pneumatic  tire,  on  wheel,  dropped  to 
the  floor  from  a  measured  distance  above,  and  tracing  its  rebounds  by  a  resiliometer, 
as  described. 

systematic  experiments  for  determining  this  point  have  been 
made.  Perhaps  the  most  exhaustive  investigations  were  those 
conducted  by  C.  E.  Duryea,  some  years  since,  by  way  of  de- 
termining the  merits  of  various  makes  of  bicycle  pneumatics.  In 
a  paper  on  the  subject  communicated  to  the  writer  and  subse- 
quently published  in  a  prominent  automobile  journal,  Mr.  Dur- 
yea writes  as  follows : 

"In  the  course  of  experiments  with  cycle  tires,  the  writer  built 
a  simple  resiliometer,  believed  to  be  the  first  in  the  United  States, 
for  the  purpose  of  testing  the  comparative  resilience  of  the  differ- 
ent tires  then  in  use.  This  device  consisted  of  a  bar  six  or  eight 


136  SELF-PROPELLED    VEHICLES. 

feet  long,  forming  an  extension  of  a  wheel  axle,  the  end  of  the  bar 
being  pivoted  to  the  wall  at  the  height  of  the  axle.  On  this  bar 
a  pencil  was  fixed  to  bear  against  a  vertical  plane  surface  adapted 
to  slide  toward  or  from  the  wheel.  On  this  surface  paper  cards 
were  attached,  and  the  tire  to  be  tested  was  placed  on  the  wheel. 
The  wheel  was  then. lifted  a  given  distance  and  supported  by  a 
prop.  Moving  the  slide  produced  on  the  card  a  line  indicating 
the  height  from  which  the  wheel  would  fall.  Tripping  the  prop 
and  moving  the  slide  at  the  same  time  produced  a  series  of  zig- 
zag lines,  as  shown  in  the  cut,  each  being  lower  than  the  pre- 
ceding in  a  practically  fixed  relation.  After  the  wheel  quit  bounc- 
ing, another  line  would  be  drawn  showing  the  normal  position 
of  the  wheel  when  resting  on  the  ground.  The  height  of  the  first 


FIG.  115.— Diagram  illustrating  resfliometer  record  of  a  pneumatic  tire,  on  wheel,  dropped 
from  a  given  distance  to  a  one-inch  rpund  rod,  and  recorded  as  the  resiliometer  slide 
is  moved. 

rebound  above  the  lower  line,  as  compared  with  the  distance 
between  the  lines,  was  taken  as  the  measure  of  the  tire's  resilience 
for  the  purpose  of  comparison  with  other  tires. 

"Many  hundreds  of  cards  were  made,  both  from  smooth  sur- 
faces and  from  obstacles,  such  as  a  one-inch  rod  resting  on  the 
floor  across  the  path  of  the  tire.  A  tire  that  gave  good  results 
from  a  smooth  surface  would  not  necessarily  give  good  results 
from  an  obstacle,  while  the  tire  that  gave  good  results  from  a 
rough  surface  generally  gave  good  results  from  a  smooth.  Tires 
of  equal  size  and  weight,  as  nearly  as  possible,  were  tested  at 
equal  air  pressures  and  also  at  different  air  pressures.  The  re- 
sults of  the  tests  showed  that  good  tires  possessed  a  resiliency  of 
eighty-five  to  ninety  per  cent,  under  favorable  circumstances, 


PNEUMA  TIC  TIRES.  137 

while  other  tires  fell  as  low  as  fifty-five  to  sixty  per  cent,  under 
the  most  favorable  tests  that  could  be  given  them — clearly  a  vast 
difference,  and  to  the  writer  an  unexpected  one. 

Tests  on  the  Quality  of  the  Fabric.— "The  tests  further 
showed  that  the  fabric  of  the  tire  should  be  free  to  yield  in  a 
direction  lengthwise  of  the  tire  and  that  the  air  should  be  con- 
fined by  threads  encircling  the  tire  transversely,  i.  e.,  around  its 
smallest  section.  These  tests  were  amply  borne  out  in  practice 
by  the  adoption  of  thread  tires,  which  are  admitted  to  be  much 
faster  than  woven  fabric  or  canvas  tires. 

"The  tests  further  demonstrated  that  the  tire  should  be  held 
on  by  some  means  other  than  the  strength  of  the  fabric,  for  if 
the  fabric  must  hold  the  tire  the  threads  must  run  more  or  less 
lengthwise  of  the  tire,  whereas,  as  already  stated,  the  best  re- 
sults were  obtained  by  placing  the  threads  crosswise  of  the  tire. 
This  same  placing  of  the  threads  has  an  advantage  in  the  matter 
of  durability,  for  it  is  quite  evident  that  the  strength  of  the  fabric 
will  be  preserved  longer  if  it  is  called  upon  to  hold  the  air  only 
than  if  doing  double  duty  by  holding  the  tire  on  the  rim  as  well. 

"A  third  factor,  which  has  an  important  bearing  on  light 
tires,  or  with  heavy  loads,  is  the  receptive  ability  of  the  tires.  If 
the  fabric  is  free  to  yield  lengthwise  the  obstacle  will  push  into 
the  tire  without  damaging  the  fabric  and  without  lifting  the  load. 
With  an  iron  tire,  for  example,  an  obstacle  like  a  marble  will 
force  the  load  to  be  lifted  over  it,  whereas  a  rubber  or  pneumatic 
tire  with  fabric  free  to  yield  lengthwise  simply  receives  the  mar- 
ble without  lifting  the  load.  Prints  of  the  positions  assumed  by 
the  surfaces  of  different  tires  were  made  by  placing  a  lead  wire 
on  the  obstacle  and  running  the  tire  over  it  under  load.  This 
outline  showed  very  conclusively  that  one  tire  would  take  its 
support  from  the  ground,  simply  swallowing  the  obstacle,  while 
the  other  attempted  to  lift  the  load  just  as  a  solid  hard  tire  would 
do,  in  which  case  the  strain  on  the  fabric  concentrated  at  the 
point  of  the  obstacle  must  be  very  great." 

Tests  on  the  Shapes  of  Rims  and  Tires — In  addition  to 
the  results  attained,  as  above,  Mr.  Duryea  also  made  cards  illus- 
trating the  relative  merits  of  single  and  double  tube  tires  and  of 
rims  of  various  shapes  and  depths.  His  conclusions  were  that : 


138 


SELF-PROPELLED   VEHICLES. 


"The  ordinary  round  tire  lying  in  an  arc-shaped  rim,  as  is  the 
common  method,  cannot  utilize  its  side  walls  properly  when 
meeting  an  obstacle,  since  it  is  flattened  toward  the  rim  and 
caused  to  bend  at  the  side  abruptly  at  two  places;  being  bent 
outward  over  the  edge  of  the  rim  and  inward  at  its  widest  point. 
The  outward  bend,  together  with  dirt  which  may  get  between 
tire  and  rim,  tends  to  chafe  the  tire  on  the  edge  of  the  rim,  a 
phenomenon  commonly  known  as  rim  cutting.  The  other  bend 
cannot  stretch  the  outer  layers  of  fabric,  so  it  must  compress 
the  inner  fabric  and  inner  rubber,  which  compression  rapidly 
causes  a  crack,  weakening  the  tire  from  the  inside,  with  the  re- 
sult that  in  a  short  while  the  tire  begins  to  swell  along  the  sides 
and  finally  bursts.  Any  rim,  therefore,  which  will  hold  the  tire 


Fio.  116.— Diagram  illustrating  the  relative  degree  of  flattening  consequent  on  deflating 
a  double-tube  pneumatic,  mechanically  secured  to  base,  and  a  cemented  single-tube 
pneumatic,  through  one-half  diameter  above  edges  of  rim.  Note  the  sharp  corners  of 
the  single  tube. 

at  the  bottom  only,  and  yet  preserve  it  from  rolling  sidewise  on 
the  rim,  is  conducive  to  long  life  of  tire,  for  it  leaves  the  side  walls 
free  from  short  bends  and  increases  the  depth  of  the  tire,  which 
increases  its  beneficial  results  as  well." 

Relative  Efficiencies  of  Tires. — In  order  to  illustrate  his  con- 
tention, Mr.  Duryea  prepared  figures  of  a  mechanically  fastened 
double-tube  tire  and  of  a  single-tube  cemented  tire  with  arc-shaped 
rim,  showing  their  shapes  when  inflated  and  when  deflated  to 
one-half  their  diameter.  His  conclusions  were  that,  since  a 
double-tube  tire  may  be  compressed  further  than  a  single-tube, 
a  small  tire  of  the  former  variety  is  as  efficient  in  smoothing  the 


PNEUMATIC  TIRES.  139 

road  as  a  larger  one  of  the  latter  variety,  while,  at  the  same  time, 
a  proportionate  deflation  of  the  two  shows  a  further  advantage, 
in  that  the  walls  of  a  double-tube  tire  are  bent  much  shorter  for 
a  given  compression  than  in  the  single  tube,  and  are  forced  against 
the  edges  of  the  'rim  with  much  less  compression,  and  that,  fur- 
ther, the  single-tube  tire  does  not  flatten  out  so  widely  in  propor- 
tion to  its  diameter  as  does  the  double  tube,  which  latter  fact  is 
of  importance,  because  added  width  means  added  supporting 
surface,  tending  to  resist  further  compression  as  it  increases.  He, 
therefore,  concludes  that : 

"The  best  automobile  tire  is  the  one  mechanically  fastened  so 
as  to  relieve  the  fabric  from  the  strain  of  holding  the  tire  in  posi- 
tion. Its  fabric  must  be  as  strong  as  possible,  because  of  the 
heavy  service  which  means  a  long  fibre  closely  woven  canvas  of 
the  greatest  possible  strength  and  the  fewest  necessary  thick- 
nesses, which  arrangement  is  less  liable  to  puncture  or  tear  than 
any  thread  fabric  and  is  yet  as  flexible  as  the  necessary  strength 
will  permit.  Being  mechanically  fastened,  the  fabric  need  not 
be  stretched  in  the  direction  of  the  length  of  the  tire  which  in- 
creases the  resilience  and  lessens  the  strain  and  liability  of  rup- 
ture in  passing  over  obstructions/' 

As  may  be  readily  understood,  a  further  advantage  gained  by 
using  a  double-tube  tire,  mechanically  fastened  at  the  base,  is  that 
the  sidewise  strains  encountered  in  turning  corners,  are  not  so 
liable  to  cause  rolling  off  the  rim.  In  bicycles  this  danger  is 
largely  averted  by  the  rake,  or  inclination,  taken  by  the  wheels 
in  turning  corners,  which  maintains  the  entire  wheel-structure, 
including  the  tire,  in  one  plane.  But,  in  automobiles  this  rake 
cannot  be  obtained  except  with  the  front  or  steer  wheels,  the 
result,  being  that  the  strain  brought  upon  a  tire  in  turning  cor- 
ners at  high  speed  is  enormous.  A  tire,  standing  high  above  the 
rim,  and  rigidly  attached  at  the  base,  is  capable  of  a  very  con- 
siderable sidewise  deformation  without  particularly  great  dan- 
ger of  rupture  or  other  accident.  Howbeit,  if  the  inflation  be-in- 
sufficient,  such  side  strains  are  very  liable  to  loosen  the  fasten- 
ings, particularly  when  clamps  are  used. 

Attachments  for  Double-Tube  Tires.— The  G.  &  J.  tire  has 
several  points  of  resemblance  to  the  Michelin  clincher.  The 
outer,  or  casing,  tube  carries  longitudinal  flanges,  intended,  as  is 


140 


SELF-PROPELLED   VEHICLES. 


shown,  to  fit  into  the  grooves  on  the  rim.  The  method  of  attach- 
ment is,  briefly,  to  insert  the  flange  on  the  side  carrying  the 
rubber  and  fabric  flap  piece,  shown  beneath  the  inner  tube ;  then 
to  set  the  inner  tube  in  place,  valve  first;  finally,  to  insert  the 
flange  on  the  side  of  the  outer  tube  still  unattached  beneath  the 
opposite  groove  on  the  rim,  and  beneath  the  flap  piece  already 
mentioned.  The  side  last  attached  is  first  disengaged  in  the  act 
of  removing  the  tire  from  the  rim.  By  inserting  the  flanges  oi 
the  outer  tube  in  the  grooves  of  the  rim  a  very  firm  grip  is  ob- 
tained, which  cannot  be  disturbed  without  the  use  of  a  special  tool 


FIG.  117.—"  Automotor  "  Gasoline  Phaeton,  with  rumble  seat,  illustrating  a  recent  design 
in  light  motor  carriage  construction. 


furnished  with  each  set  of  these  tires.  Moreover,  this  secure  at- 
tachment at  the  base  of  the  tube  neutralizes  the  tendency  to  creep, 
which  effect  is  greatly  increased  by  perfect  inflation.  The  secure 
attachment,  obtained  by  the  flanges,  is  augmented  in  the  Michelin 
tires  by  the  use  of  such  lugs  and  screws  as  are  shown  in  connec- 
tion with  the  type  of  tire  described  above.  The  danger  of  punc- 
ture is  largely  overcome  in  this  tire  by  thickening  and  corrugat- 
ing the  tread,  but  should  puncture  ever  occur,  it  is  possible  to 
readily  detach  the  outer  tube  from  the  wheel  rim,  in  order  to 
apply  the  necessary  cement  and  patches  to  the  inner. 


PNEUMATIC  TIRES.  141 

The  Dunlop  Double-Tube  Tire.  —  With  the  Dunlop  double- 
tube  carriage  tire  the  process  of  attaching  is  somewhat  similar, 
although  the  flanges  are  here  replaced  by  one  or  several  endless 
wire  rings,  inserted  in  the  fabric  of  the  outer  tube,  and  of  such 
length  as  to  fit  the  rim  tightly  at  the  base  of  the  tubular  retaining 
flanges  or  edges,  as  shown,  when  the  inner  tube  is  inflated.  The 
process  of  attachment  of  the  outer  tube  is,  briefly,  to  insert  the 
wire  edge  of  one  side  of  the  outer  tube  in  the  bottom  of  the  deep 
central  channel  of  the  rim,  which,  as  may  be  readily  understood, 
permits  the  ring  to  be  forced  over  the  tubular  edges  with  very 
slight  effort.  The  inner  tube  is  then  put  into  place,  valve  first, 
after  which  the  other  wire  ring  is  inserted  in  the  bottom  of  the 
central  channel  and  similarly  urged  over  the  edges  of  the  rim.  By 
inflating  the  inner  tube,  the  wire  rings  are  forced  against  the 
bases  of  the  tubular  edges ;  all  tendency  to  roll  or  pull  off  under 
this  outward  stress  being  thus  overcome.  A  very  firm  and  rigid 
attachment  is  also  made  at  the  base,  completely  around  the  rim, 
with  the  result  that  creeping  is  rendered  impossible.  The  tubular 
retaining  edges  obviate  rim-cutting,  as  the  tire  is  forced  against 
them,  under  the  weight  of  the  carriage.  The  layer  of  fabric  at  the 
base  of  the  inner  tube  eliminates  all  tendency  to  pinching  or  wear- 
ing of  the  rubber  against  the  corners  of  the  case  tube,  which  was 
a  constant  source  of  anxiety  in  some  of  the  earlier  patterns  of  this 
tire  made  without  such  protection.  Some  Dunlop  tires,  intended 
for  heavier  service,  have  an  additional,  detachable  tread-piece, 
which  may  be  readily  replaced  by  proper  appliances  when  worn, 
thus  ensuring  a  much  longer  life  to  the  tire  and  acting  as  an 
additional  precaution  against  puncture. 

The  Goodyear  Tire.— The  theory  of  producing  firm  attach- 
ment between  tire  and  rim  by  the  use  of  endless  wire  rings,  or 
bands,  is  also  applied  in  the  Goodyear  vehicle  tire,  as  is  shown 
in  an  accompanying  figure.  The  walls  and  tread  of  this  tire  are 
composed  of  the  usual  layers  of  fabric  and  rubber,  which  .are  con- 
tinued also  into  the  square  portion  intended  to  fit  the  rim.  At 
either  side  of  the  base,  and  so  disposed  as  to  bear  against  the 
outwardly  flang-ed  edges  of  the  rim  channel,  are  ribbons  of  wire 
inserted  in  the  fabric  of  the  tire  wall.  The  wires  of  these  ribbons 
are  braided  together,  like  the  threads  of  a  cotton  shoe  string  or  a 


142 


SELF-PROPELLED   VEHICLES. 


binding  tape,  so  as  to  shorten  in  length  under  any  impulse  to 
spread  the  strands  apart.  The  braiding,  being  thus  spread  by  the 
inflation  of  the  tire,  contracts  in  length  so  as  to  grip  the  rim  very 
firmly,  and  prevents  all  creeping  or  other  movement  tending  to 
cut  either  the  wire  or  the  fabric.  The  arrangement  permits  the 
use  of  a  shallower  rim  than  is  possible  with  most  other  pneumatic 
tires. 

A  Non-Collapsible  Tire. — The  Munger  single  tube  tire,  as 
shown  in  Fig.  105,  bears  on  its  upper  and  lower  walls  longitudinal 
rubber  buffers,  so  shaped  as  to  fit  together  in  case  the  tire  be- 


Fio.  118.— Wheels  and  running:  gear  of  a  "  track-laying  "  tractor,  designed  to  travel  on 
ordinary  roads  with  a  small  amount  of  surface  friction  without  the  use  of  pneumatic 
tires. 

comes  deflated  from  any  cause.  In  this  contingency  it  is  not 
necessary  that  the  wheel  should  run  on  its  rim,  to  its  obvious 
destruction,  since  these  buffers  prevent  complete  collapse  and  to 
a  large  extent  give  the  effect  of  a  solid  tire.  The  tread  buffer  also 
renders  puncture  from  sharp  obstacles  an  exceedingly  remote 
possibility.  It  further  presents  a  greater  surface  than  does  the 
ordinary,  round-faced  tire  for  the  displacement  of  air,  and,  as  a 
result,  can  be  used  with  less  inflation  with  consequently  better 
resiliency  and  power  to  absorb  vibration.  One  disadvantage, 
however,  lies  in  the  lips  overhanging  the  edges  of  the  rims,  which 
would  seem  to  prevent  the  sides  from  bending  as  freely  as  de- 
sirable. 


PNEUMATIC  TIRES.  143 

Tractive  Devices:  Track-Laying  Wheels —In  order  to  at- 
tain the  end  of  superior  traction,  otherwise  than  by  the  use  of 
pneumatic  tires,  several  investors  have  devised  and  patented  road 
locomotives  that  lay  a  track  as  they  advance.  This  is  accom- 
plished by  the  use  of  a  suitably  constructed  chain  belt  passing 
around  the  wheels  of  the  vehicle  and  driving  them  from  a 
sprocket  directly  geared,  or  on  a  countershaft.  One  of  the  best 
designed  of  these  is  shown  in  an  accompanying  figure.  It  would 
undoubtedly  serve  the  ends  of  ready  traction  and  power  economy, 
but  has  never  been  tested  under  high  speed  conditions.  Gen- 
erally speaking,  it  seems  hardly  suitable  for  motor  carriage  pur- 
poses, and  is  mentioned  only  to  show  that  the  necessity  met  by 
pneumatic  tires  has  been  repeatedly  apprehended  by  vehicle  de- 
signers. 

A  Double  Interacting  Elastic  Wheel — Another  device  of 
more  recent  invention  and  even  greater  excellence  of  design  de- 
serves mention  in  this  connection.  It  is,  in  short,  a  wheel  con- 
trived to  combine  the  durability  and  good  tractive  properties  of  a 
solid  tire  with  the  resiliency  of  a  pneumatic,  while  quite  effectu- 
ally protecting  the  latter  from  puncture  and  other  wearing 
strains  of  travel.  These  ends  are  achieved  with  a  very  ingenious 
mechanism,  by  which  two  wheels  are  hung  on  one  hub  or  axle 
boss,  as  shown  in  the  accompanying  diagram,  the  outer  one 
being  shod  with  an  ordinary  solid  tire,  the  inner  with  a  pneu- 
matic. Of  course,  in  order  that  the  desired  effect  should  be  per- 
fectly achieved,  it  is  necessary  that  there  should  be  some  play 
between  the  two  wheels,  permitting  the  weight  of  the  vehicle  to 
bear  against  the  lowest  point  of  the  pneumatic  tire  on  the  inner 
wheel,  without  involving  distortion  of  any  part  of  the  structure. 
Accordingly,  the  hub  is  constructed  in  sections,  between  which 
considerable  movement  is  possible.  These  sections,  as  construct 
ed  for  several  types  of  these  wheels,  are  shown  in  accompanying 
sketches,  and  are,  briefly :  A  central  hub  plate— or  spoke  hanger 
where  wire  spokes  are  used— which  is  perforated  to  fit  loosely 
over  the  axle  boss,  and  has  also  a  slot  cut  on  two  opposite  radii 
from  the  nave;  two  other  hub  plates,  or  "half  hubs,"  similarly 
perforated  and  interiorlv  slotted,  and  also  arranged  for  attaching 
spokes;  two  "intermediate  floating  euide  plates,"  with  keys 
upon  reverse  sides  at  right  angles  to  each  other,  which  guide 


144  SELF-PROPELLED   VEHICLES. 

plates,  being  set  between  each  of  the  outer  hub  plates  and  the 
central  hub,  have  their  keys  or  splines  inserted  in  the  grooves 
above  mentioned,  thus  permitting  a  complete  rotative  move- 
ment between  the  central  hub  and  the  outer  hub  plates,  which 
gives  the  desired  play  between  the  former  and  the  two  latter. 


FIG.  119.— The  Double  Interacting  Wheel,  constructed  for  heavy  carriage  use.  As  may 
be  seen,  it  consists  of  two  distinct  wheels  hung  on  one  axle  and  in  the  same  plane. 
The  larger  has  a  solid  rubber  tire  for  the  sake  of  good  traction,  the  smaller  has  a 
pneumatic  for  the  needed  resilient  effect. 

Construction  of  the  Double  Interacting  Wheel.— The  central 
hub  supports  the  spokes  of  the  outer,  or  larger,  wheel,  which  is 
shod  with  the  solid  rubber  tire,  and  the  outer  hub  plates  attach 
similarly  from  either  side  to  the  inner,  or  smaller,  wheel,  which 
is  shod  with  the  pneumatic.  Since  the  hub  of  this  inner,  or 
smaller,  wheel  fits  snugly  over  the  axle  boss,  the  outer  one  hav- 


PNEUMATIC  TIRES.  145 

ing  considerable  play  around  it,  it  follows  that  the  effect  of  the 
load  is  to  bring  the  weight  upon  the  pneumatic  tire,  which  bears 
against  a  circular  channel,  thus  delivering  the  benefit  of  its  re- 
siliency to  nearly  one-half  the  wheel  diameter,  rather  than  to 
only  one  point  at  the  ground.  Thus,  while  a  free  movement  radi- 
ally is  permitted  by  the  interaction  of  the  wheels,  they  are  so 
locked,  by  the  keys  or  splines  on  the  floating  guide  plates  of  the 
hub,  that  they  are  compelled  to  rotate  together.  A  wheel  thus 
constructed  may  be  tested  in  the  manner  above  specified,  and 
will  show  the  effect  of  the  pneumatic  tire's  resiliency,  as  much,  if 
not  more,  than  if  the  tire  were  mounted  on  the  outer  rim  in 


FIG.  120.— Elements  of  the  Compound  Hub  of  the  Double  Interacting  Wheel.  A  is  the 
outer  hub  plate,  showing  interior  slot.  B  is  one  of  the  two  floating  guide  plates,  car- 
rying keys  or  splines,  arranged  on  either  side,  as  indicated.  C  is  the  central  hub 
plate,  also  slotted,  and  arranged  for  hanging  spokes. 

contact  with  the  ground.  At  the  same  time  the  tire  is  perfectly 
protected  from  puncture;  is  not  liable  to  creep,  since  the  strain 
of  the  load,  delivered  at  the  point  of  contact  on  the  outer  rim, 
is  transmitted  through  a  V-shaped  area  to  the  interior  of  the 
wheel,  thus  involving  that  the  pneumatic  tire  be  bound  by  a 
considerable  arc  of  its  outside  containing  channel.  Such  a  con- 
struction and  operation  also  prevent  destruction  of  the  pneu- 
matic from  other  causes,  such  as  wrenching  and  kneading  on 
the  rim,  that  result  in  tearing  and  overheating.  This  means  that 
a  cheaper  pneumatic  tube  may  be  used  than  would  be  possible 
against  the  ground  under  heavy  load. 


CHAPTER  ELEVEN. 

ON    THE    CONSTRUCTION    AND     OPERATION     OF     BRAKES    ON 
MOTOR  CARRIAGES. 

General  Requirements  in  Brakes.— An  important  subject  in 
connection  with  the  construction  and  operation  of  motor  vehicles 
relates  to  the  brakes  used  for  retarding  the  movement  of  the  car- 
riage when  it  is  desirable  to  either  come  to  a  more  or  less  sudden 
stop,  or  to  hold  th^  carriage  stationary  on  the  side  of  an  incline. 
Several  conditions  are  essential  to  the  designing  of  brakes  for 
motor  carriages,  among  which  we  may  mention  ease  and  rapidity 
of  operation  and  the  maximum  of  braking  effect,  with  the  mini- 
mum of  power  exerted  at  the  operating  lever. 

Varieties  of  Construction  in  Brakes. — There  are  two  kinds 
ot  brakes  in  familiar  use  on  vehicles  of  all  descriptions :  Shoe 
brakes,  which  operate  by  the  pressure  of  the  contact  surface  or 
shoe  upon  the  periphery  of  the  wheel  tire,  and  drum  brakes, 
which  operate  by  tightening  a  band  around  a  drum,  either  on  the 
hub  of  the  wheel  or  on  the  case  of  the  differential  gear.  Both 
varieties  are  used  to  a  considerable  extent  on  motor  vehicles,  al- 
though most  authorities  agree  that  shoe  brakes  are  unsuitable 
for  use  on  wheels  tired  with  pneumatic  tubes.  The  reason  given, 
for  this  opinion  is  that  the  constricting  effort  due  to  pressing  the 
shoe  against  the  tire  is,  like  the  ordinary  shocks  experienced  in 
travel,  largely  absorbed  by  the  tire  itself,  with  the  result  that  it 
is  liable  to  be  rent  or  torn  from  its  attachment  to  the  rim.  On 
the  other  hand,  it  has  been  asserted  by  at  least  one  well-known 
manufacturer  of  motor  vehicles  that  shoe  brakes  may  be  safely 
and  satisfactorily  used  on  pneumatic-tired  wheels,  provided  the 
surface  contact  of  the  shoes  extend  over  a  sufficiently  extensive 
arc  to  prevent  the  strain  from  being  concentrated  on  small  areas 
of  the  circumference.  This  authority  asserts  that  he  himself  has 
used  a  motor  tricycle  for  several  years,  the  wheels  of  which  are 
equipped  with  a  shoe  brake  constructed  according  to  his  idea. 
The  result  is,  he  states,  that  the  contact  surface  of  the  shoe  has 
been  worn  much  more  rapidly  than  the  tire  surface,  which  seems 
to  suffer  very  little,  if  any,  more  than  would  be  the  case  with  the 

146 


CONSTRUCTION  AND  OPERATION  OF  BRAKES.          147 

use  of  any  other  form  of  brake.  Whether  his  experience  in  this 
regard  would  be  borne  out  in  general  practice,  it  is  not  necessary 
to  inquire,  the  fact  being  that  nearly  all  motor  vehicles  at  the 
present  time  operate  with  drum  and  strap  brakes, 

Principles  of  Band  Brake  Operation. — Among  the  advan- 
tages possibly  to  be  alleged  for  the  drum  and  band  brake  we  may 
enumerate  the  facts  that,  with  ordinary  connections,  they  are 
much  more  readily  operated  and  with  much  greater  effect  while 
on  any  showing  involving  a  minimum  of  wear  on  the  moving 
parts.  As  may  be  readily  understood,  the  operation  of  the  drum 
and  band  brake  is  a  reversed  application  of  the  principle  of 
torque,  as  already  explained  in  connection  with  the  electrical 
motor.  As  there  explained,  if  the  power  acting  upon  a  rotating 
shaft  be  equal  to  the  weight  of  fifty  pounds  constantly  applied, 
and  the  pulley  attached  to  the  shaft  be  twice  the  diameter  of  the 
shaft,  the  available  power  at  the  periphery  of  the  pulley  will  be 
just  one-half  that  exerted  on  the  periphery  of  the  shaft  itself. 
This  statement  is  equivalent  to  saying  that  if  a  rope  carrying  a 
weight  of  fifty  pounds  be  wound  about  a  pulley,  whose  diameter 
is  one  foot,  mounted  on  a  shaft,  whose  diameter  is  six  inches, 
it  will  exactly  balance  a  weight  of  one  hundred  pounds  on  a  rope 
wound  about  the  shaft.  The  constantly  applied  power  of  slightly 
over  twenty-five  pounds  at  the  periphery  of  the  pulley  will  be 
sufficient  to  rotate  the  shaft  against  a  resistance  of  fifty  pounds 
on  the  shaft.  It  thus  appears  that  the  braking  power,  applied 
around  the  periphery  of  the  brake  drum,  is  efficient  in  retarding 
the  momentum  of  a  forward-moving  vehicle  in  very  nearly  the 
inverted  ratio  existing  between  the  diameters  of  the  drum,  or 
pulley,  and  the  rotating  shaft  to  which  it  is  attached.  In  the 
practical  application  of  this  principle,  however,  it  is  obvious  that 
there  must  be  very  definite  limits  to  the  diameter  of  the  brake 
drum,  or  pulley,  beyond  which  it  would  be  undesirable  to  go. 
According  to  the  practice  adopted  by  light  motor  vehicle  manu- 
facturers, the  average  diameters  of  brake  drums  range  between 
eight  inches  and  two  feet,  the  principal  item  of  variation  in  this 
respect  being  the  weight  of  the  vehicle  itself. 

Beaumont's  Formulae  for  Brakes.— It  is  possible  to  obtain  a 
very  efficient  band  brake  on  a  very  moderate  diameter  of  drum, 


148 


SELF-PROPELLED   VEHICLES. 


owing  to  the  fact,  which  need  scarcely  be  mentioned,  that  the 
braking  effort  is  never  applied  until  the  motive  power  is  discon- 
nected from  the  running  gear.  In  a  steam  vehicle,  the  first  act  is 
to  shut  off  the  steam  from  the  cylinder ;  in  a  gasoline  vehicle,  to 
throw  off  the  main  clutch ;  in  an  electrical  vehicle,  to  open  the 
circuit  of  the  motor  and  batteries.  The  resistance  against  which 
the  brake  must  then  operate  is  found  to  be  purely  a  consideration 


FIG.  121.— The  Hub  Brake  and  Operating  Levers  Used  on  the  Panhard  Carriages.— The 
arm,  F,  being  pushed  in  the  direction  of  the  arrow,  causes  the  arm,  G,  on  the  same 
pivot,  H,  to  move  in  the  opposite  direction,  as  indicated  by  the  lower  arrow.  Through 
this  arm,  G,  runs  the  cable,  J,  as  shown,  \vhich,  pulling  on  the  arm,  K,  pivoted  at  /, 
pulls  the  strap,  shown  by  dotted  lines  around  the  drum,  S.  The  other  end  of  the 
strap  attached  to  the  short  arm  of  the  lever,  K,  is  thus  drawn  toward  the  same  point; 
a  tight  frictional  bind  being  the  result. 

of  the  vehicle's  weight,  its  velocity  and  the  acceleration  due  to 
gravity.  This  principle  is  already  stated  by  Mr.  Beaumont,  as 
follows: 

"When  it  is  necessary  to  determine  the  brake  power  to  stop  a 
vehicle  of  a  given  weight  running  at  a  given  speed,  in  a  given 
distance,  and,  by  this  means,  arrive  at  something  like  due  com- 
prehension of  the  necessary  parts  brought  into  play  to  effect  this 
stop,  it  must  first  be  pointed  out  to  those  who  overlook  the  fact, 
that  the  strain  put  upon  a  brake  to  effect  a  stop  in  a  given  dis- 
tance increases  as  the  square  of  the  increase  of  speed;  so  that 
to  stop  a  car  running  twenty  miles  per  hour  requires  four  times 


CONSTRUCTION  AND  OPERATION  OF  BRAKES. 


149 


the  power  necessary  to  stop  it  in  the  same  distance  when  run- 
ning ten  miles  per  hour.  Commonly,  all  calculations  relating  to 
the  acceleration  of  masses  at  high  speed  are  calculated  on  the 
basis  of  distance  covered  in  feet  per  second,  and  hence  the  work 
or  energy  lodged  in  a  mass  having  a  given  weight  and  moving 
at  a  given  velocity  in  feet  per  second  is  given  by  the  following 
expression : 

K  =  ^ir 

in  which  K  represents  the  work,  or  energy,  lodged  in  the  mov- 
ing mass ;  W  represents  its  weight ;  v,  its  velocity,  expressed  in 


FIG.  122.  Fl°-  123- 

FIGS.  122  and  123.- Two  Forms  of  Constricting  Band  Brake.  In  the  first  figure,  the  drum, 
E,  rotates  on  the  spindle,  D.  Two  shoes,  F  and  G,  joined  to  the  link,  L,  pivoted  at  J, 
are  pressed  against  the  periphery  of  the  drum,  E,  when  the  link,  K,  moves  the  lever 
H,  pivoted  at  C,  so  as  to  pull  the  arm,  A,  on  F,  by  compressing  the  spring,  B,  no 

In  the1seSfndhngu?e,athe  band,  D.  surrounding  the  drum,  G,  is  drawn  tight   when  the  link 
A,  operates  the  bell  crank,  B,  thus  producing  a  pull  through  its  attach meni 
and  E. 

feet  per  second,  and  g,  the  acceleration  due  to  gravity,  or  32.2 
feet  per  second." 

From  the  above  formula,  Mr.  Beaumont  proceeds  to  derive 
other  essential  elements,  such  as  the  efficient  power  necessarily 


150  SELF-PROPELLED    VEHICLES. 

applied  to  stop  a  vehicle  of  given  weight,  in  a  given  length  of 
travel. 

Reducing  the  expression  for  feet  per  second  to  miles  per  hour, 
according  to  the  usual  standard,  and,  assuming  the  weight  of  the 
vehicle  to  be  one  ton  (of  2,240  pounds),  he  reduces  the  formula, 
as  follows:  One  mile  being  5,280  feet,  and  one  hour,  3,600 
seconds, 

1  mile  per  hour  =  0*         =  1.466   feet  per  second, 
o,  oUU 

Whence  W  v2         W   x    (1.466)2       W  X  2.15 

TT  ~60~  -OUT       =  Wx  0.0334. 

Then  a  vehicle  weighing  one  ton,  traveling  at  ten  and  twenty 
miles  per  hour,  by  the  formula, 

K=  W  V'  X  0.0334, 

in  which  F  represents  miles  per  hour,  will  be  for  10  miles 
2,240  ^X  100  X  0.0334  =  ?,480  foot  pounds;  for  20  miles 
2,240  'x  400  X  0.0334  =  29,920  foot  pounds. 

To  Find  Distance  in  Which  Brakes  Will  Act  on  Vehicle's 
Speed. — Then,  taking  k  as  the  coefficient  of  friction  between  the 
tires  and  road  surface,  which  is  approximately  0.60  for  rubber 
tires ;  and  taking  W  as  the  proportion  of  the  total  weight  carried 
by  the  wheels  to  which  the  brake  is  applied,  which  may  be  as- 
sumed to  be  0.6  of  the  whole,  the  maximum  distance  required  to 
stop  the  vehicle  on  the  level,  on  an  ordinary  road,  whose  surface 
resistance  is,  supposedly,  included  in  the  expression,  k,  may  be 
expressed  by  /,  as  follows : 

W  V2  X  0.0334 


k  w 

Then,  for  a  vehicle  weighing  one  ton,  tired  with  average  rub- 
ber tires,  traveling  at  a  momentum  of  10  and  20  miles  per  hour, 
respectively,  we  have: 

9'3  feet  at  10  miles> 


n  aOAA 
O.o  X  1,044 

9Q  Q90 

1  =  0.6  X  T'44  =  37.1  feet  at  20  miles; 

these  distances  representing  the  maximum,  with  a  braking  effect 
sufficient  to  cause  the  wheels  to  skid. 


CONSTRUCTION  AND  OPERA  TION  OF  BRAKES. 


151 


To  Find  the  Required  Braking  Pull.— In  order  to  find  the 
necessary  pull,  p,  on  the  brake  band,  the  following  formula  is 
given : 

W  V2  X  .0334 


p  =  lc  w  = 


I 


which  for  one  typical  vehicle,  moving  at  20  miles   per  hour, 
gives, 

29,920 


P  = 


37.1 


=  806  pounds. 


FIG.  124. 


FIG.  125. 


FIGS.  124  and  125.— Two  Forms  of  Expanding  Band  Brake.  In  the  first  figure,  t  he  gear,  G, 
nas  an  Internal  bearing  surface,  within  which  is  the  band,  C,  pivoted  at  A,  a  point 
separate  from  G.  The  arm,  B,  of  the  bell  crank,  B  D,  being  moved  to  the  left,  spreads 
apart  the  two  links,  E  and  F,  connected  to  D  at  H,  thus  pressing  both  ends  of  the 
band,  C,  against  the  internal  bearing  surface  of  G,  and  producing  the  necessary  brak- 
ing friction. 

In  the  second  figure,  the  gear,  A,  similarly  arranged  with  an  internal  bearing  surface, 
contains  the  expanding  band,  B.  When  the  link,  C,  is  pulled,  the  lever  arm,  D,  double- 
pivoted  at  E  and  F,  causes  the  two  ends  of  the  band,  B,  to  press  against  the  internal 
bearing  surface  of  A,  thus  creating  friction.  The  spring  shown  normally  holds  the 
two  ends  of  the  band  apart. 

Varieties  of  Drum  and  Band  Brake. — As  shown  by  accom- 
panying illustrations,  there  are  two  general  types  of  drum  brake, 
the  first  consisting  of  a  drum  or  pulley,  around  the  circumfer- 
ence of  which  is  a  metal  strap  faced  with  leather,  which  is  drawn 
tight  whenever  it  is  desired  to  furnish  the  resistance  necessary  to 
check  the  rotation  of  the  shaft ;  and  expanding  band  brakes,  in 
which  a  similar  metal  strap,  faced  with  leather  or  other  suitable 
substance  acts  against  the  internal  surface  of  a  rotating  drum  or 
pulley.  The  former  type  is,  however,  at  the  present  time  the 
most  usual  construction,  although  the  latter  is  seeing  an  increas- 
ing popularity. 


152 


SELF-PROPELLED    VEHICLES. 


In  some  forms  of  constricting  band  brakes,  instead  of  a  metal 
strap  extending  entirely  around  the  drum,  two  shoes  pivoted  at 
a  certain  point,  and  having  their  inside  faces  faced  with  leather, 
are  tightened  against  the  drum  by  a  suitable  lever.  In  practically 
all  forms  of  expanding  band  brake  the  band  is  attached  to  the 
outside  frame,  at  one  point  of  its  circumference,  and  is  suitably 
tightened  by  a  toggle  joint  operated  by  a  lever.  This  is  the  plan 
adopted  in  the  several  types  shown  in  the  accompanying  illus- 
trations, 


FIG.  126.— The  "  Duryea  "  Expanding  Break.  The  two  ends  of  the  metal  band  are  sepa- 
rated by  the  lever,  A,  and  the  adjusting  screw,  B,  which  is  swiveled  to  the  hinge,  C. 
A  forward  pull  on  lever,  A,  through  the  chain  pull,  indicated  by  D,  causes  the  two 
ends  of  the  band  to  be  thrust  apart  and  bear  against  the  inner  surface  of  the  sprocket. 
The  extension  spring,  E,  normally  holds  the  band  away  from  this  friction  surface. 
The  two  lugs,  F  F,  attached  to  a  spider  hung  on  the  axis  of  the  sprocket,  take  the 
braking  effort  from  the  bottom  of  the  band  more  into  the  line  of  travel.  A  frame- 
work, indicated  at  H  and  I,  supports  a  leather  guard  covering  both  the  chain  and 
sprocket. 

The  Care  of  Brakes. — In  successfully  operating  a  motor  car- 
riage it  is  particularly  essential  that  the  brakes  should  be  main- 
tained in  good  working  order.  This  involves  that  the  levers  and 
connections  should  at  all  times  operate  perfectly,  and  that  no 
worn  or  loose  bearings  should  be  neglected.  Furthermore,  and 
most  important,  the  friction  surface  between  the  band  and  the 
drum  should  be  constantly  and  carefully  guarded  from  oil  de- 
posits, which  will  certainly  render  the  braking  effort  useless.  If 
oil  collects  between  the  band  and  the  drum  surface  it  may  be  cut 
out  with  gasoline,  and  the  parts  then  carefully  wiped  with  a  suit- 
able rag. 


CHAPTER  TWELVE. 

ON  BALL  AND  ROLLER  BEARINGS  FOR  MOTOR  CARRIAGE  USE. 

The  General  Uses  of  Rotative  Bearings. — The  practical 
problems  involved  in  the  construction  of  bicycles  and  motor  car- 
riages have  given  a  great  popularity  to  ball  and  roller  bearings 
for  use  in  connection  with  almost  every  variety  of  rotating  shaft. 
As  we  have  already  seen  in  several  constructions  mentioned  in 
previous  parts  of  this  volume,  ball  bearings  are  used  in  a  large 
variety  of  different  devices,  in  order  to  allow  of  the  greatest  pos- 
sible ease  in  turning  with  the  smallest  friction  and  wear.  The 
most  important  use,  however,  for  ball  and  roller  bearings,  in  both 
bicycles  and  motor  carriages,  is  on  the  axles  of  the  road  wheels. 
For  this  purpose,  although  ball  bearings  are  eminently  satisfac- 
tory on  the  wheel  axles  and  pedals  of  bicycles,  they  are  for  a 
number  of  reasons  unsuitable  for  the  heavier  weights  and  higher 
speeds  of  motor  carriages.  Accordingly  roller  bearings  have 
taken  their  place  almost  exclusively  in  this  connection. 

Rotating  Supports  vs.  Sliding  Surfaces. — The  principal  ob- 
ject involved  in  using  ball  and  roller  bearings  on  bicycles  and 
motor  carriages  is  to  secure  economy  of  traction  effort,  with  ease 
and  rapidity  of  driving,  as  well  as  a  minimum  of  starting  effort 
at  the  beginning  of  travel.  A  few  simple  principles  will  serve  to 
fully  explain  the  reasons  for  this  fact.  When  we  have  a  plain 
wheel  bearing,  such  as  is  used  on  ordinary  horse  carriages,  con- 
sisting of  a  simple  tapered  boss,  with  a  similarly  shaped  hollow 
axle-box  rotating  around  it,  there  is  a  considerable  effort  neces- 
sary at  starting  from  rest,  a  good  proportion  of  the  power  being 
consumed  in  resisting  the  friction  between  the  sliding  surfaces. 
This  resistance  is  very  largely  due  to  adhesion  between  the  two 
sliding  surfaces,  due  to  cohesion  of  the  lubricating  oil  or  grease. 
As  a  matter  of  fact,  it  may  be  easily  understood  that  the  sliding 
action  of  two  round  surfaces,  one  within  another,  may  be  readily 
compared  to  the  sliding  of  one  plane  surface  upon  another.  The 
first  difference  in  point  of  resistance  and  effort  necessary  to  over- 
come inertia,  as  between  two  such  surfaces,  when  sliding  against 

153 


154 


SELF-PROPELLED    VEHICLES. 


one  another  directly,  and  when  some  kind  of  rollers  or  rotating 
supports  are  interposed,  is  a  matter  of  the  commonest  experi- 
ence. The  heaviest  objects  may  be  readily  moved  or  slid  along 
the  ground  when  rollers  are  placed  beneath  them;  also  the 
heaviest  loads  when  carried  on  wheels  of  suitable  breadth  and 
diameter  may  be  handled  with  a  degree  of  ease,  increasing  di- 
rectly as  the  ideal  conditions  are  approximated.  This  principle  is 
the  very  one  that  is  applied  in  the  practice  of  substituting  ball 
and  roller  bearings  for  ordinary  plain  bearings.  Instead  of  two 
plane  surfaces  having  rollers  interposed,  the  two  surfaces  are 
given  a  rounded  contour,  the  one  being  within  the  other,  and  the 
same  rule  of  increased  ease  of  relative  movement  applies. 


FIG.  127.— One  Form  of  Driving  Axle  Using  Ball  Bearings.  The  hub  is  secured  in  place  by 
the  nuts  and  binders  shown  at  A,  B,  C,  D,  E.  At  its  inner  extremity  it  carries  a  cone, 
F,  which  works  on  the  ball  race,  G.  The  hub  is  thus  suspended  on  the  ball  race,  which 
also  acts  to  neutralize  end  thrusts. 

Rotative  Bearings  vs.  Plain  Bearings. — The  obvious  reason 
for  the  superior  traction  qualities  obtained  by  the  use  of  both 
kinds  of  rotative  bearings  is  that  the  friction  and  resistance  be- 
tween the  relatively  moving  surfaces  is  so  greatly  distributed  that 
it  is  reduced  to  a  practically  negligible  quantity. 

One  of  the  most  familiar  evidences  of  loss  in  power  through 
the  friction  of  the  sliding  surfaces,  in  plain  bearing  wheels,  is  seen 
in  the  fact  that  the  hubs  speedily  become  loose,  greatly  to  the 
detriment  of  balanced  rotation  of  the  wheels  and  waste  of  trac- 
tion effort.  With  properly  adjusted  ball  or  roller  bearings  this 
icsult  is  indefinitely  delayed,  even  where  it  is  not  entirely  obvi- 
ated, and  the  wheels  on  which  they  are  used  not  only  give  the 


BALL   AND    ROLLER  BEARINGS. 


155 


best  results  in  point  of  tractive  efficiency,  but  also  in  the  duration 
of  their  period  of  usefulness. 

The  Limitations  of  Ball  Bearings — Of  the  two  varieties  of 
rotative  bearing,  however,  we  may  state  on  the  authority  of  sev- 
eral writers  on  the  subject  that  ball  bearings  have  very  decided 
limitations  in  point  of  useful  operation  as  compared  with  cylin- 
drical roller  bearing  surfaces.  Balls  have  been  successfully  used 
on  bicycles  and  numerous  other  constructions,  but  even  at  their 


FIG.  128.— Stud  Steering  Axle  showing  Hub  hung  on  Conical  Roller  Bearings.  The  shape 
of  the  bearings  serves  the  double  purpose  of  securing  perfect  rotative  movement  in 
forward  travel;  also  to  take  up  end  thrusts. 

best  involve  a  considerable  loss  of  power,  owing  to  the  fact  that 
they  roll  in  opposite  directions  and  constantly  rub  against  one 
another,  with  the  result  that  the  friction  speedily  wears  them  out, 
involving  constant  necessity  of  repairs.  Furthermore,  as  the 
pressure  of  the  load  must  necessarily  come  on  one  point  only  at 
a  time,  there  is  a  limit  to  the  weight  which  can  be  carried  suc- 
cessfully without  crushing  one  or  several  balls  and  jamming  the 
ball  race. 

When  the  balls  are  confined  by  flat  cones,  heavy  pressure  upon 
single  points  causes  crystallization  and  speedy  deterioration.  To 
remedy  this  defect  some  builders  have  curved  the  cones  to  fit  the 


156  SELF-PROPELLED    VEHICLES. 

balls  as  nearly  as  possible,  with  the  result  of  reducing  the  wear, 
but  increasing  the  friction,  since  there  is  then  no  longer  a  simple 
rolling  action  between  the  balls  and  cones.  Others  have  adopted 
the  plan  of  staggering  the  balls  so  that  they  travel  upon  different 
surfaces  of  the  cones ;  but  this  expedient  also  involves  consid- 
erable wear  and  friction  of  the  ball  surfaces,  and  crystallization 
follows  much  more  speedily. 

The  Conditions  of  Using  Roller  Bearings. — Very  largely 
from  the  reasons  already  enumerated,  the  roller  bearings  have 
come  into  almost  universal  use  for  the  road  wheels  of  motor  car- 
riages. As  stated  by  a  prominent  manufacturer  of  roller  bear- 
ings, we  have  it  that  "for  heavy  weights  it  would  seem  that  a 
greater  rolling  surface  must  be  obtained  before  we  can  have  a 
successful  bearing,  and  yet,  combined  with  this  greater  rolling 
surface,  there  must  be  a  purely  rolling  action  to  eliminate  the 
wear  that  results  from  rubbing  and  crystallization." 

As  stated  by  a  noted  authority,  the  peculiar  advantage  of  the 
roller  bearing  lies  in  the  fact  that  in  the  ideal  conditions  there  is 
no  relative  sliding,  and,  therefore,  theoretically,  no  friction.  As 
also  stated  by  him,  however,  there  are  several  difficulties  in  the 
way  of  obtaining  the  theoretically  perfect  conditions  in  practical 
operation.  These  are :  (i)  the  concentration  of  the  load  upon 
points ;  (2)  the  almost  insurmountable  difficulty  of  obtaining  truly 
circular  cylindrical  rollers ;  (3)  the  friction  on  the  surfaces  of  the 
rollers  themselves;  (4)  the  difficulty  of  adjustment;  (5)  the  lack 
of  parallelism  when  the  rollers  are  slightly  worn ;  (6)  the  difficulty 
of  providing  for  end  thrusts  or  side  pressures ;  (7)  the  blows  and 
shocks  resulting  when  wearing  has  occurred  on  the  surfaces  of 
the  rollers.  He  further  explains  that  to  any  extent  whatever, 
however  small,  that  the  surface  of  contact  deviates  from  the 
theoretical  or  geometrical  line,  the  action  between  the  two  sur- 
faces deviates  from  the  theoretically  perfect  rolling  contact,  in- 
volving sliding  or  frictional  contact  proportionate  to  the  de- 
formation of  the  roller.  The  principal  cause  for  the  breaking  of 
roller  bearings,  which  is  so  fertile  a  source  of  annoyance  and 
disablement  to  the  road  wheels  of  motor  carriages,  is  due  to  the 
hammering  action  resulting  when  any  single  roller  lacks  in  the 
point  of  uniformity  of  hardening  with  its  mates,  which  results  in 
a  greater  initial  strain  in  its  material. 


BALL   AND   ROLLER  BEARINGS.  157 

Constructional  Points  on  Roller  Bearings  — Given  the  best 
possible  process  available  to  the  practical  machinist  for  the  needs 
of  adequately  shaping  and  hardening  rollers,  the  problem  of  the 
best  construction  becomes  almost  entirely  one  of  proper  assem- 
bling of  the  several  parts.  As  shown  by  the  accompanying  il- 
lustration, the  usual  method  of  mounting  roller  bearings  is  to 
enclose  them  in  a  suitable  case,  in  which  the  several  cylindrical 
rollers  are  separated,  so  that,  rotating  on  their  own  axes,  their 
surfaces  do  not  come  into  contact.  It  is  a  very  usual  practice  to 
include  end  thrust  ball  bearings  at  the  extremities  of  the  roller 
cylinders,  so  as  to  still  further  reduce  the  wear  and  friction  inci- 
dent on  the  rotation  of  the  several  cylinders. 

One  of  the  most  excellent  types  of  roller  bearing  for  motor 
carriages  is  the  "American"  roller  bearing,  which,  as  shown  by 


FIG.  129.— Roller  Bearings  Enclosed  in  a  Retaining  Cage.  The  bearings  are  hung  to  the 
two  end  pieces  of  the  cage,  being  separated  by  stationary  pieces  of  metal.  The  inner 
tube  is  the  rotating  axle;  the  outer,  the  axle  box. 

the  accompanying  illustrations,  consists  of  a  set  of  main  rollers 
intended  directly  to  sustain  the  weight,  and  running  in  races  on 
the  hub  and  on  the  axle.  These  main  rollers  are  separated  and 
guided  by  intermediate  separating  rollers,  whose  office  is  solely 
that  of  separating  and  guiding.  These  separating  rollers  are  con- 
fined between  the  centres  of  the  .main  rollers  and  overlap  their 
ends,  their  action  being  entirely  rolling.  The  supports  of  these 
separating  rollers  are  had  in  three  rings  held  in  place  by  the 
flange  ends  of  the  separators  and  running  in  narrow  beveled 
grooves  in  the  separators  and  in  the  fixed  caps  which  enclose  the 
entire  mechanism.  The  rolling  parts  are  so  arranged  that  the 
separators  engage  their  supports  in  perfect  harmony  with  the 
main  rollers,  traveling  just  fast  enough  to  keep  up  with  them  in 
going  about  the  axle,  thus  avoiding  both  dragging  and  pushing. 


158 


SELF-PROPELLED    VEHICLES 


In  this  type  of  bearing  the  end  thrttst  is  entirely  taken  by 
bevels,  on  the  principle  of  the  flanges  on  car  wheels,  this  con- 
struction involving  that  there  is  no  rubbing  friction ;  the  action 
between  the  ends  of  the  roller  and  bevels,  being  purely  a  rolling 
one,  they  are  thrust  against  each  other.  As  claimed  by  the  manu- 


FIG.  130. — Sectional  Diagrams  of  the  "American"  Roller  Bearing.  These  bearings  are 
beveled  at  the  ends,  as  indicated,  the  bevels  taking  up  the  end  thrusts,  and  are  sepa'- 
rated  by  smaller  rollers,  one  of  which  is  shown  below  the  larger  figures.  These  sepa- 
rating rollers  do  not  come  into  contact  with  the  rotating  axle. 

facturers,  the  separators  hold  the  main  rollers  far  better  than  any 
cage  could,  while  the  wear  upon  them  is  practically  negligible, 
the  result  being  that  the  main  rollers  are  never  allowed  to  twist 
around,  as  is  frequenty  the  case  in  caged  bearings. 


CHAPTER   THIRTEEN. 

ON  THE  NATURE  AND  USE  OF  LUBRICANTS. 

Of  Lubricants  for  Various  Purposes.— One  of  the  most  im- 
portant considerations  in  connection  with  the  operation  of  a 
motor  vehicle,  of  any  power,  relates  to  the  proper  lubrication  of 
the  moving  parts.  As  is  perfectly  evident  on  reflection,  it  is 
necessary  that  all  such  parts  should  be  supplied  with  oil  or  lubri- 
cating grease,  but  it  is  also  a  fact,  not  so  well  understood,  that 
different  kinds  of  lubricant  are  necessary  to  the  different  kinds 
of  mechanisms. 

Of  Lubricants  for  Gasoline  Engine  Cylinders. — Every  re- 
liable dealer  in  lubricants  has  a  specially  prepared  grade  of  oil 
for  a  gas  engine  cylinder,  and  still  another  for  use  in  the  cylinder 
of  a  steam  engine,  and  all  agree  to  the  statement,  that  the  kind  of 
lubricant  suitable  in  one  case  is  wholly  useless  in  the  other.  The 
primary  reason  for  this  distinction  is  that,  as  we  have  seen,  the 
cylinder  of  a  gas  engine  operates  under  a  far  higher  temperature 
than  is  possible  even  in  a  steam  engine,  and  consequently  the 
oils  intended  for  use  in  the  former  case  must  be  of  such  a  quality 
that  the  point  at  which  they  will  burn  and  carbonize  from  heat 
is  as  high  as  possible.  Furthermore,  it  is  essential  in  a  gas  en- 
gine cylinder  that  the  oil  should  be  constantly  supplied,  and  for 
the  purpose  of  properly  meeting  this  requirement  a  number  of- 
different  kinds  of  dripping  and  filtering  oil  cups  have  been  de- 
vised and  put  into  practical  use. 

Requirements  in  Gas  Engine  Lubricants. — As  has  been  re- 
peatedly pointed  out  by  gas  engine  authorities,  the  apparently 
long  period  spent  in  finally  perfecting  the  motor  was  due  almost 
entirely  to  the  fact  that  the  subject  of  proper  lubrication  was  not 
fully  understood.  With  the  ordinary  oils,  which  are  sufficiently 
suitable  for  use  in  the  steam  engine  cylinder,  it  was  impossible 
to  obtain  anything  like  a  satisfactory  speed  and  power  efficiency, 
and  only  when  the  superior  properties  of  mineral  oils  were  bet- 
ter understood  was  the  present  high  degree  of  perfection  in  any 

159 


160  SELF-PROPELLED    VEHICLES. 

sense  obtainable.  Even  to  the  present  day  the  question  of  proper 
lubricants  for  gas  engines  is  most  essential,  and,  as  has  been  per- 
tinently remarked,  "the  saving  of  a  few  cents  per  gallon  in  pur- 
chasing a  cheaper  grade  of  oil  for  this  purpose  is  the  most  ex- 
pensive kind  of  economy  imaginable."  The  general  qualities  es- 
sential in  a  lubricating  oil  for  use  on  gas  engine  cylinders  in- 
clude a  "flashing  point  of  not  less  than  360°,  Fahrenheit,  and 
fire  test  of  at  least  420°,  together  with  a  specific  gravity  of  25.8 
and  a  viscosity  of  175." 


FIG.  131.  FIG.  131a.  FIG.  131b. 

FIGS.  131,  131a,  131b.  —  Three  Forms  of  Adjustable  Oil  Feeding  Cup.  In  the  first  and 
second  figures,  the  flow  of  oil  is  regulatfd  by  the  thumb  screw  at  the  top.  This  allows 
the  oil  to  drip  at  any  required  rate.  The  first  figure  shows  a  "sight-feed  oil  cup," 
which,  as  shown,  means  that  the  rate  and  constancy  of  the  feed  may  be  seen  through 
the  section  of  glass  tube  at  the  base.  In  the  third  figure,  the  hand-wheel  at  the  top 
is  merely  for  filling  the  reservoir,  the  amount  of  flow  being  regulated  by  the  cocks  at 
the  base.  By  regulating  the  flow  by  the  right-hand  cock,  the  left-hand  acts  only  to 
open  and  close  the  vent,  permitting  a  flow  of  no  more  and  no  less  than  that  deter- 
mined by  the  right-hand  cock.  All  three  forms  are  used  on  automobiles,  although 
the  first  two  are  the  most  common.  The  first  is  used  for  cylinder  lubrication. 

Some  Objections  to  Organic  Oils. — While  a  number  of  ani- 
mal and  vegetable  oils  have  a  flashing  point,  and  yield  a  fire  test 
sufficiently  high  to  come  within  the  figures  specified,  they  all 
contain  acids  or  other  substances  which  have  a  harmful  effect  on 
the  metal  surfaces  it  is  intended  to  lubricate.  In  addition  to  this, 
their  tendency  to  gum  or  congeal  under  certain  conditions  of 
temperature  or  pressure  render  them  unfit  for  the  purpose  of  gas 
engine  lubrication, 


THE  NATURE  AND   USE  Ot  LUBRICANTS.  161 

The  Use  of  Graphite  as  a  Lubricant.— Many  authorities 
strongly  recommend  the  use  of  powdered  or  flaked  graphite  in 
the  cylinders  of  explosive  engines  for  the  reason  that  this  sub- 
stance is  one  of  the  most  efficient  of  solid  lubricants,  especially 
at  high  temperatures.  It  has  been  found  especially  useful  in 
some  steam  engine  cylinders  and  in  general  on  the  bearings  and 
moving  parts  liable  to  become  overheated.  According  to  sev- 
eral well-known  authorities,  it  is  well  adapted  for  use  under  both 
light  and  heavy  pressures  when  mixed  with  certain  oils.  It  is 
also  especially  valuable  in  preventing  abrasion  and  cutting  under 
heavy  loads  and  at  low  velocities. 

In  using  graphite  as  a  lubricant,  it  is  positively  essential  to  re- 
member one  thing:  It  is,  as  said,  very  useful  for  certain  pur- 
poses, when  mixed  with  some  liquid  oil  lubricants.  However,  it 
is  impossible  to  use  it  in  connection  with  oils  that  are  to  be  fil- 
tered through  the  small  orifices  of  constant  feed  oil  cups,  as  on 
the  cylinders  and  bearings  of  engines.  The  reason  for  this  is 
that  it  will  not  flow  through  small  holes,  even  when  mixed  with 
very  thin  oil;  and  the  very  cooling  of  a  bearing  will  cause  the 
graphite,  mixed  with  oil,  to  clog  up  the  oil  hole  to  an  extent  that 
may  not  be  remedied  by  the  reheating  of  the  bearing,  after  the 
stoppage  of  the  lubricant.  On  the  same  account,  it  is  essential 
that  the  diameter  of  ..the  oil  conduit  to  any  moving  part  be  as- 
certained to  be  of  suitable  shape  and  proportions  before  the  use 
of  any  solid  lubricant  is  attempted. 

The  Tests  and  Qualities  of  Lubricating  Oils.— It  is  per- 
fectly possible  to  use  an  oil  having  a  fire  test  at  the  point  already 
mentioned  in  a  gas  engine  cylinder  whose  temperature  at  ex- 
plosion is  nearly  four  times  greater,  because  with  a^properly  ad- 
justed water  circulation  the  burning  and  carbonization  of  the  oil 
is  constantly  prevented.  The  heat-absorbing  action  of  the  jacket 
water  is  also  efficient  in  retaining  at  the  required  point^the  vis- 
cosity of  the  oil— which  is  to  say,  the  quality  of  dripping  at  a 
certain  ascertained  rate  through  a  narrow  aperture  under  press- 
ure. This  quality  virtually  refers  to  the  thinness  of  the  oil.  A 
well-known  manufacturer  of  lubricating  oils  for  gas  engine  cylin- 
ders well  states  the  ideal  qualities  to  be  sought,  as  follow: 
"There  is  no  danger  of  this  oil  burning  or  smoking  in  the  cylii 
der  and  thus  causing  a  carbonaceous  deposit,  which  so  seriously 


102  SELF-PROPELLED    VEHICLES. 

interferes  with  the  proper  running  of  the  engine.  We  have  re- 
peatedly known  of  this  oil,  when  put  into  a  cylinder  which  had 
not  been  properly  cleaned,  cutting  out  the  carbonaceous  matter 
that  had  accumulated  from  the  use  of  an  inferior  oil,  after  which 
the  cylinder  would  remain  clean  and  polished  by  the  action  of 
the  oil  alone."  Combined  with  these  ideal  elements,  the  claim  is 
made  that  this  particular  variety  of  oil  has  a  very  low  "cold 
test,"  with  the  very  necessary  insurance  against  congealing,  and 
consequent  delay  and  inconvenience  in  starting  the  engine.  Its 
resistance  to  heat  is  also  placed  at  such  a  figure  that  it  will  not 
become  unusually  thin  as  will  some  qualities  of  oil,  the  reason 
being  that  its  viscosity  is  maintained  at  the  desired  point. 

In  choosing  lubricants  for  any  of  the  moving  parts  of  a  self- 
propelled  road  vehicle  it  is  especially  essential  to  see  that  the 
quality  of  resisting  temperatures,  both  high  and  low,  without 
change  of  useful  consistency,  should  be  present.  An  oil  that  will 
congeal  at  ordinary  low  temperatures,  or  become  thin  at  ordi- 
nary high  temperatures,  is,  of  course,  entirely  unsuitable  for  this 
purpose.  Furthermore,  the  quality  of  flowing  freely  from  well- 
adjusted  oil  cups  should  be  assured,  since  the  high  speed  of  auto- 
mobile engines  engendering  a  constant  vibration,  affecting  more 
or  less  the  adjustment,  involves  that  the  oil  supplied  should  be  a 
subject  of  constant  solicitude.  To  state  the  matter  in  a  few 
words,  all  competent  authorities  seem  to  agree  that  the  condi- 
tions of  automobile  operation  require  the  use  of  mineral  oils  ort 
all  moving  parts  and  the  avoidance  of  any  mixture  with  animal 
or  vegetable  oils,  which,  although  frequently  used  in  stationary 
engines,  cannot  but  result  in  inconvenience,  not  to  say  disaster, 
in  automobile  practice. 

Since  most  manufacturers  of  motors  and  vehicles  furnish  mod- 
erately full  directions  for  dealing  with  the  question  of  lubrication, 
many  of  them  offering  for  sale  brands  of  oil  which  have  been 
carefully  tested  by  themselves,  it  will  be  hardly  necessary  to  add 
more  to  the  principles  already  laid  down.  If  the  automobile 
driver  constantly  bears  in -mind  the  fact  that  an  oil  suitable  for 
one  portion  of  his  machinery  is  not  of  necessity  suitable  for  every 
other,  and  will  observe  the  conditions  essential  to  maintaining 
the  oil  used  at  its  proper  consistency,  he  will  have  little  trouble 
upon  this  score. 


THE,   NATURE   AND    USE    OF   LUBRICANTS.  163 

Oil  Pumps  and  Circulation. — With  the  use  of  high-speed 
gasoline  engines,  it  has  been  found  necessary  to  use  a  forced  cir- 
culation of  the  oil  in  order  to  completely  lubricate  the  interior  of 
the  cylinder.  The  most  usual  method  with  high-powered  multiple- 
cylinder  engines  is  to  employ  a  positively  geared  pump  to  force 
the  oil  through  adjustable  sight-feed  conduits  to  the  various  mov- 
ing parts.  Such  pumps,  operating  in  ratio  to  the  speed  of  the 
engine,  of  course  supply  lubricant  more  rapidly  as  the  number 
of  revolutions  increases,  and  slow  down  as  they  decrease.  Thus, 
a  perfect  supply  is  maintained,  as  required,  on  the  one  hand,  and 
flooding  is  prevented  on  the  other.  There  are  several  efficient 
types  of  oil  pump  on  the  market,  all  working  on  the  same  prin- 
ciple of  forcing  the  oil  to  the  moving  parts  in  such  volumes  as 
may  be  determined  by  the  adjustment.  One  or  two  inventors 
have  produced  devices  of  this  kind  operated  by  compressed  air 
forcing  the  oil  out  of  a  tank,  the  degree  of  compression  being 
determined  by  the  speed  of  the  engine  operating  the  air  pump. 
Such  a  device  has  its  advantages,,  but  is  not  as  serviceable  as  an 
ordinary  oil  force  'pump,  and  is  much  more  complicated. 

Several  modern  gasoline  engines,  notably  the  Locomobile  and 
Winton,  have  the  lubricating  apparatus  arranged  as  an  integral 
part  of  the  mechanism.  The  former,  as  subsequently  explained, 
uses  the  splash  system,  whereby  oil  fed  by  gravity  from  a  tank 
at  the  level  of  the  cylinder  head,  flows  into  the  crank  case,  whence 
it  is  splashed  over  the  piston  and  the  wrist  and  crank  bearings. 
The  Winton  engine  has  an  oil  pump  enclosed  in  the  case,  and 
the  oil,  being  forced  from  this  into  a  special  chamber,  is  dis- 
tributed to  all  the  moving  parts,  as  required.  Other  engines  use 
types  of  multiple  oiler,  from  which  the  oil  is  carried  to  the  parts 
through  adjustable  sight-feed  conduits. 

Where  horizontal  cylinders  are  used,  it  is  frequently  customary 
to  use  single  grease  cups  of  the  general  type  shown  in  the  fore- 
going figures,  and  to  control  the  feed  by  mechanical  pressure 
from  the  cap.  Such  arrangements  are  less  suitable  for  vertical 
cylinders,  which  require  oil  in  large  quantities  and  some  degree 
of  exact  adjustment  in  its  flow.  Indeed,  one  very  useful  feature 
of  the  oil  pump  lubrication  is  that  the  flow  of  oil  may  be  kept  in 
ratio  to  the  speed  of  the  engine.  This  is  a  very  necessary  feature, 
since,  with  an  even  flow,  flooding  is  liable  to  result. 


164  SHIF-PROPELLED  VEHICLES. 

Points  on  Lubrication. — The  first  important  consideration  in- 
volved in  preparing  a  carriage  for  a  run  is  to  see  that  the  moving 
parts  are  properly  lubricated.  Every  carriage  or  motor  is  sold 
with  directions  for  providing  for  this  necessity,  the  rate  of  oil 
consumption  and  the  quantity  being  specifically  designated.  The 
principal  parts  which  it  is  particularly  necessary  to  keep  thor- 
oughly oiled  are  the  cylinder  pistons,  the  bearings  of  the  crank 
shafts  and  fly-wheels,  the  differential  gear  drum  and  the  change 
speed  gearing. 

Since  on  most  well-built  motors  and  carriages  the  moving  parts 
are  supplied  with  lubricating  oil  by  means  of  sight  feed  oil  cups, 
of  familiar  design,  it  is  necessary  to  do  no  more  than  to  see  that 
the  required  level  of  oil  is  always  maintained.  As  specified  by 
many  motor  carriage  authorities,  it  is  desirable  to  thoroughly  ex- 
amine and  replenish  the  oil  supply  in  the  adjustable  feed  cups 
at  the  end  of  about  every  thirty  miles  of  run.  Another  con- 
sideration of  importance  in  this  particular  is  that  before  re- 
plenishing the  supply  cf  oil  to  such  parts  as  the  crank  case  or  the 
differential  gear,  the  old  lubricant  should  be  thoroughly  evacuated 
by  means  of  the  vent  cocks  supplied  in  each  case.  The  reason 
for  this  is  that,  after  a  run  of  from  twenty  to  thirty  miles,  the 
oil  in  the  moving  parts  is  apt  to  be  largely  contaminated  with  dust 
and  other  impurities,  which  tend  to  interfere  with  its  usefulness 
as  a  lubricant, 


CHAPTER    FOURTEEN. 

GENERAL   PRINCIPLES   OF   GAS   ENGINE   OPERATION. 

Advantages     of     Internal     Combustion    flotors.  —It     has 

been  frequently  said  that  steam  is  the  best  available  motive 
power  found  under  ordinary  conditions  for  utilizing  the  vast 
expansive  energy  of  heat.  At  a  certain  temperature  water 
assumes  the  gaseous  state,  and  its  power  of  expansion  is  so 
immense  that,  when  properly  confined,  it  will  displace  any  mov- 
able obstacle  in  its  effort  to  assume  greater  proportions ;  thus 
furnishing  the  force  for  driving  machinery.  Vaporized  water, 
however,  is  not  the  only  gas  possessing  such  properties.  In  cer- 
tain aspects,  it  is  also  not  the  most  convenient  medium  for  trans- 
forming heat  into  motive  energy,  particularly  for  small  power 
motors.  This  is  true  because  the  steam  engine,  as  we  have  seen, 
requires  a  boiler  or  generator  to  produce  the  steam  and  a  con- 
stant source  of  heat  to  accomplish  this  effect.  The  consequence 
is  that  a  large  percentage  of  the  heat  units  employed  is  actually 
wasted,  even  in  the  best-designed  engines.  This  result  is  in- 
evitable, because  the  fuel  for  combustion,  the  fluid  to  be  vappr- 
ized  by  heat,  and  the  engine  to  be  driven  by  the  expansive  energy 
are  all  separate  and  distinct  elements,  requiring,  frequently,  elab- 
orate devices  to  secure  the  end  of  co-operation  as  a  practical 
working  unity.  If,  now,  the  expansive  energy  can  be  derived 
direct  from  the  fuel  and  the  ignition  effected  by  an  intermittent 
source  of  heat,  it  is  obvious  that  the  machine  is  simplified  and 
the  total  economy  increased.  In  other  words,  when  some  such 
rapidly-acting  expansive  force,  as  is  found  in  the  explosion  of 
gunpowder,  can  be  so  controlled  and  utilized  as  to  drive  a  piston, 
as  a  gun  throws  forth  its  projectile,  or  bullet,  we  have  achieved 
the  end  of  transforming  heat  into  power  with  the  smallest  pos- 
sible waste.  In  the  steam  engine  one  large  percentage  of  heat 
is  wasted  in  raising  the  water  to  the  boiling  point;  another,  in 
maintaining  the  degree  of  temperature  necessary  to  continual 
generation  of  steam ;  a  third,  by  being  absorbed  in  the  cylinders 
as  a  necessary  means  for  preventing  a  checking  of  expansion. 
Furthermore,  the  chimney  draught,  requisite  to  combustion  in 

165 


166  SELF-PROPELLED    VEHICLES. 

the  heater  and  as  an  escape  for  burned  products,  acts  as  a  waste 
in  expelling  considerable  heat  through  the  flue.  The  nearest 
approach  to  the  ideal  of  economy  in  the  steam  engine  is  found  in 
the  ''flash  boiler,"  as  devised  by  Leon  Serpollet,  and  others, 
wherein  water  injected  into  narrow  tubes,  already  raised  to  a 
high  temperature  by  contact  with  fire,  is  instantaneously,  or  ex- 
plosively, transformed  into  expansile  vapor,  to  be  fed  to  cylin- 
ders, also  at  a  high  initial  temperature.  Even  this  system  in- 
volves considerable  waste,  from  the  necessity  of  maintaining  the 
"flash  tubes"  at  the  required  temperature,  between  the  periods 
of  injection;  the  wear  and  corrosion  on  the  metal  parts  is  also 
excessive.  On  the  whole,  its  disadvantages  are  numerous,  and 
render  it  a  very  poor  substitute  for  an  internal  combustion 
motor,  like  the  modern  gas  engine. 

The  Requirements  in  Explosive  Motors. — The  internal  com- 
bustion or  explosive  engine  possesses  most  of  the  desirable  feat- 
ures, which  the  steam  engine  lacks,  and  realizes  many  of  the 
requirements  of  an  ideal  motor.  Its  fuel,  a  hydrocarbon  gas  or 
liquid,  is  properly  mixed  with  air,  fed  direct  to  the  cylinders,  and 
ignited  explosively,  so  as  to  be  raised  instantly  to  its  highest 
temperature  point,  by  an  intermittent  source  of  heat,  all  in  the 
same  small  chamber.  It  is,  therefore,  merely  a  cylinder  and 
driving  gear,  without  boiler  or  furnace  attachments ;  and,  on  this 
account,  affords  a  high  power  efficiency,  in  proportion  to  its  total 
size  and  weight.  For  use  in  motor  carriages,  internal  com- 
bustion motors  must  be  provided  with  some  device  for  producing 
the  explosive  gas  from  a  suitable  liquid ;  since  it  is  both  incon- 
venient and  impracticable  to  carry  it  stored  in  tanks  or  bottles, 
which  must  be  constantly  charged  under  high  pressure.  Such  a 
liquid,  moreover,  must  be  one  that  is  readily  mixed  with  atmos- 
pheric air,  passed  through  it,  or  over  it,  in  a  specially  designed 
vessel,  comrfionly  called  a  carburetter,  or  vaporizer,  so  as  to 
form  a  true  gas  with  inflammable  properties.  Several  hydro- 
carbons, such  as  benzine,  gasoline,  and  some  forms  of  alcohol, 
are  suitable,  although  gasoline  has  been  most  generally  adopted 
for  this  purpose. 

Operation  of  an  Explosive  Motor. — The  cylinder  of  a  gas- 
oline motor  is,  as  in  most  gas  engines,  open  at  the  end  toward  the 


GAS  ENGINE   OPERATION. 


167 


crank  shaft.  Admission  for  the  fuel  gas  at  the  opposite  end, 
which  is  normally  closed,  is  had  by  mushroom  valves  operated 
usually  by  suction  of  the  descending  piston.  The  piston  is,  there- 
fore, single-acting,  or  moved  by  an  impulse  from  one  direction 


FIG.  132.— The  Cycle  of  an  Otto,  or  Four-Part  Cycle,  Gas  Engine. 

only,  and  is  of  the  "trunk"  pattern,  having  the  swinging  con- 
necting rod  pivoted  within.  The  action  of  the  piston  and  driving 
gear  is,  thus,  entirely  positive  and  automatic,  in  the  sense  that 
there  is  no  pressure  whatever  outside  of  the  cylinder — as  in  the 


168  SELF-PROPELLED    VEHICLES. 

steam  engine — to  effect  movements  of  the  parts,  when  proper 
valves  are  opened.  An  automobile  motor  is  started  by  turning  a 
crank  on  the  driving  shaft  a  sufficient  number  of  times  to  carry 
the  gears,  cams  and  valves  through  the  charging,  compression 
strokes,  to  the  moment  of  ignition,  when  it  will  "take  up  its 
cycle,"  and  run  by  the  power  generated  in  itself.  The  cylinder 
is  charged  by  an  out  stroke  of  the  piston,  creating  a  vacuum 
behind  it  and  drawing  in  the  mixture  of  air  and  gasoline  gas 
formed  in  the  carburetter.  With  some  carburetters  this  is  too 
"rich"  to  burn  readily,  so  a  quantity  of  pure  air  is  also  drawn  in. 
With  better  carburetters  the  mixture  needs  no  more  air. 
The  charge  is  then  compressed  by  the  return  stroke 
of  the  piston,  which  act  secures  complete  carburiza- 
tion  of  the  contained  air,  and  reduces  it  to  the  proper 
degree  of  mixture  to  be  kindled  by  the  igniting  spark  or 
other  source  of  firing.  This  causes  it  to  explode,  or  to  expand 
suddenly  and  with  great  effect,  and  drive  the  piston  outward 
again.  The  fourth  stroke,  which  is  the- one  immediately  follow- 
ing the  explosion,  is  known  as  the  "scavenging"  stroke,  from  the 
fact  that  the  piston,  moving  back  again  in  the  cylinder,  expels 
the  products  of  combustion  through  exhaust  valves  which  are 
operated  by  cams.  This  process  completed,  the  parts. are  in 
position  for  a  repetition  of  the  process ;  the  valves  for  admitting 
gasoline  gas  to  the  cylinder  then  being  opened  again. 

The  Cycle  of  a  Gas  Engine.  —These  four  strokes — two  out- 
ward and  two  inward — are  called  a  "cycle,"  and,  as  may  be  read- 
ily understood,  there  is  thus  only  one  power  impulse  for  every 
two  revolutions  of  the  fly-wheel.  This  power  stroke  also  con- 
tinues while  the  crank  is  traveling  through  half  a  revolution,  or 
through  an  arc  of  180  degrees.  It  is  also  evident  that  the  cam 
shaft,  for  operating  the  valve  system  of  the  cylinder,  revolves  but 
once  for  every  two  revolutions  of  the  crank  shaft,  with  which  it 
is  geared.  Thus  is  secured  the  opening  of  the  charging,  or 
"inhaust,"  valve,  and  of  the  scavenging,  or  exhaust,  at  precisely 
the  proper  points  in  the  cycle.  The  operation  of  a  four-cycle 
gas  engine  may  be  understood  from  this  figure :  Supposing  we 
have  a  four-cylinder  motor,  the  cranks  of  whose  four  pistons  are 
so  fixed  that,  counting  from  i  to  4,  we  have  pistons,  cams  and 
valves  in  positions  representing  the  four  cycles.  That  is  to  say, 


GAS  ENGINE   OP  ERA  7  ION. 


169 


the  first  cylinder  would  be  performing  the  inhaust  stroke;  the 
second,  the  compression;  the  third,  the  explosion;  the  fourth, 
the  scavenging.  In  such  an  engine  the  crank  would  be  turned 
by  a  steady  impulse,  since  in  some  one  of  the  four  the  explosion 
would  be  due  in  every  90  degrees  of  its  rotation.  Also  every  one 
of  the  four  cycles  would  be  taking  place  contemporaneously. 
Thus,  may  be  understood  the  process  essential  to  the  operation 
of  a  gas  engine  of  the  "Otto,"  or  "Beau  de  Rochas"  four-cycle 
type. 

Two-Cycle  Engines. — Practically  all  carriage  motors  are  built 
for  the  four-cycle  system,  which  requires  two  complete  revolu- 
tions of  the  fly-wheel  to  perform  the  four  necessary  acts  involved 
in  the  use  of  gas  as  a  motive  power.  There  is,  however,  a  method 


FIG,  133.— Diagram  of  the  stages  of  a  Two-Part  Cycle  Gas  Engine.  The  out-stroke  is  from 
left  to  right;  the  in-stroke  from  right  to  left.  The  inner  circle  around  the  crank 
shows  the  stages  of  compression,  supply,  suction,  which  take  place  within  the  crank 
case  in  front  of  the  piston.  The  outer  circle  shows  the  stages  of  explosion,  expansion, 
exhaust  and  compression,  which  take  place  behind  the  piston  in  the  combustion  space 
of  the  cylinder. 

of  accomplishing  the  same  results  in  one  revolution,  and  it  is, 
accordingly,  known  as  the  two-cycle  system.  It  uses  one  rotation 
and  two  strokes,  the  functions  of  the  two  omitted  strokes  being 
provided  for  by  certain  peculiarities  of  construction.  Its  essen- 
tial features  are  as  follows :  (i)  An  enclosed  crank  case,  such  as 
is  also  used  on  most  vehicle  motors,  is  fitted  with  a  valve  geared 
to  open  and  admit  fuel  gas  at  the  front,  instead  of  at  the  rear  of 
the  piston,  on  the  first  inward  stroke  of  the  piston.  (2)  The 
inhaust  and  exhaust  ports  of  the  cylinder  are  located  at  points 
about  midway  in  its  length,  so  as  to  be  uncovered  by  the  piston 
in  its  downward  stroke.  The  exhaust  being  reached  first,  the 


170  SELF-PROPELLED    VEHICLES. 

products  of  combustion  start  to  leave  the  cylinder,  partly  tfirough 
their  tendency  to  expand,  before  the  fresh  supply  begins  entering 
from  the  enclosed  crank  case.  (3)  At  the  end  of  the  piston,  and 
so  placed  as  to  come  opposite  the  entry  port  for  the  fresh  charge, 
when  it  is  opened,  is  a  longitudinal  plate  or  screen,  which  deflects 
the  new  gas  to  the  top  of  the  cylinder  chamber,  thus  causing  it 
to  assist  in  the  work  of  expelling  the  burned  products.  This  work 
•is  further  completed  as  the  piston  starts  on  its  return  stroke. 

The  four  acts,  admission,  compression,  ignition  and  scaveng- 
ing, are  thus  accomplished  during  one  revolution  of  the  fly-wheel 
by  the  use  of  two  chambers.  The  fuel  gas  is  admitted  to  the 
closed  crank  case  during  the  inward  stroke  of  the  piston,  at  the 
completion  of  which  the  supply  valve  is  closed.  On  the  return, 
or  outward,  stroke  this  gas  is  suitably  compressed  to  about  five 
pounds  to  the  square  inch,  which  pressure  causes  it  to  rush  into 
the  cylinder  the  moment  the  supply  port  is  opened.  When  both 
the  supply  port  and  exhaust  port  have  been  closed  by  the  inward 
stroke  of  the  piston,  the  contained  fuel  gas  is  still  further  com- 
pressed, and  is  ready  for  ignition,  as  the  piston  reaches  the  end  of 
the  cylinder.  The  next  outward  stroke  is  under  power  impulse, 
as  indeed  is  every  outward  stroke  on  the  two-cycle  arrangement ; 
each  inward  stroke  accomplishing  the  results  of  supply  and 
cylinder  compression,  and  each  outward  stroke,  the  results  of 
ignition,  exhaust  and  recharging. 

Two-Cycle  flotors  for  Vehicle  Use. — While  it  would  seem 
from  the  theory  of  the  two-cycle  motor  that  it  should  be  capable 
of  a  higher  degree  of  power  as  well  as  a  greater  speed — features 
which  should  render  it  the  ideal  motor  for  vehicles — it  is,  never- 
theless, true  that  its  practical  performance  is  otherwise.  It  is  a 
very  satisfactory  type  of  engine  for  low  speed  purposes,  and  in 
such  conditions  will  develop,  as  some  claim,  a  power  fully  50  or 
60  per  cent,  greater  than  with  a  four-cycle  engine  of  the  same 
dimensions.  This  statement  is  questioned  by  other  authorities, 
but,  as  may  be  readily  understood,  an  engine  giving  a  power 
impulse  stroke  in  every  revolution  should,  theoretically,  have 
twice  the  available  power  capacity  of  one  having  a  power  stroke 
in  every  two  revolutions  only.  This  would  undoubtedly  give 
about  the  practical  percentage  of  superiority  named  above.  At 
high  speeds,  such  as  are  contemplated  in  the  construction  of 


GAS  ENGINE   OPERATION. 


171 


motor  carriages,  the  trouble  with  the  two-cycle  motor  is  that,  all 
the  functions  of  inhaust,  compression,  ignition  and  exhaust 
being  performed  in  a  single  stroke  of  the  piston,  sufficient  time 
is  not  allowed  for  the  expulsion  of  the  burned  gases,  with  the 
result  that  the  cylinder  "chokes  itself  up,"  as  the  saying  is, 
and  its  contents  fall  below  the  explodable  point,  stopping  the 
engine.  It  is  thus  estimated  that,  while  a  four-cycle  engine  of 
a  given  horse-power  will  run  at  as  high  a  speed  as  1,200  or 
1,500  revolutions  per  minute,  a  two-cycle  engine  of  the  same 
power  can  make  no  more  than  300  or  350  revolutions.  The  same 


FIG  134.-Diagram  showing  the  Essential  Features  of  a  Typical  Carriage  Motor,  as  used 
on  the  De  Dion  Vehicles.     M  is  the  motor;  C,  the  carburetter;  S,  the  muffler;  F,  tn 
sparking  battery;  B,  the  induction  coil  and  condenser;  Q,  the  pipe  admitting  pure 
to  the  carburetter;  aa,  pipe  for  bringing  hot  air  from  around  exhaust  pipe;  e,  exnausi 
into  muffler;  a,  pipe  admitting  gas  to  cylinder;  ae,  gasoline  feed  to  carburetter;  oc, 
port  for  admitting  water  to  the  jacket  space  of  the  cylinder;  sc,  exit  por 
water  jacket. 

defect  in  operation  prevents  the  two-cycle  motor  from  attaining 
the  power  efficiency,  otherwise  seemingly  involved  in  its  con- 
structional theory.  It  is  on  these  accounts  that  the  two-cycle 
type  of  motor  has  thus  far  proved  unavailable  for  automobile 
purposes,  where  the  four-cycle  engine  has  proved  eminently 
effective. 

The  Essentials  of  a  Vehicle  Hotor.— Every  gasoline  vehicle 
must  carry  its  supply  of  fuel  spirit  in  a  tank  or  receptacle  with 
suitable  outlet  valves,  through  which  it  may  be  drawn  as 


172 


SELF-PROPELLED    VEHICLES. 


required.  The  motor  proper  consists  of  three  parts;  the  car- 
buretter, or  vaporizer,  in  which  the  liquid  hydro-carbon  is  trans- 
formed into  vapor;  the  cylinder,  to  which  it  is  admitted  by  suc- 
tion, mixed  with  a  suitable  supply  of  pure  air,  compressed  and 
ignited,  and  an  ignition  apparatus  for  producing  the  spark  or  hot 
surface  essential  to  explosion.  So  far  as  the  operation  of  the 
cylinder  is  concerned  there  are  two  general  types  of  engine : 


FIG.  135.— Section  through  a  typical  Float-Feed  Carburetter 


This  particular  device  is  th« 


one  shown  in  the  previous  cut.  Here  A  is  the  hollow  cj  indrical  float;  B,  the  spindle 
of  the  needle  valve;  C,  tube  for  admitting  hot  air  around  base  of  spraying  nozzle;  D, 
adjusting  screw  for  the  needle  valve;  H,  adjustable  air  valve;  I,  outlet  for  fuel 
mixture  to  cylinder;  J,  adjustable  opening  for  air;  K,  arm  for  attaching  throttling 
lever;  N,  spraying  nozzle;  O,  P,  screw  caps  on  channel  fromfloat  chamber;  S,  adjust- 
ing screw  for  regulating  gasoline  spray;  T,  air  vent;  G,  filtering  gauze. 

scavenging  engines,  in  which  all  the  burned-out  gases  are  ex- 
pelled from  the  cylinder,  and  non-scavenging  engines,  so  con- 
structed and  operated  that  a  certain  portion  of  these  residua  are 
retained  in  the  clearance. 

There  are  two  general  types  of  carburetter :  surface  carburet- 
ters that  operate  by  evaporation,  and  float-feed  carburetters,  or 
sprayers.  A  third  variety  of  carburetting  device  is  recognized 
by  some  authorities  in  the  type  of  gasoline  outlet  valves,  such  as 


GAS  ENGINE   OPERATION. 


173 


the  James-Lunkenheimer,  or  the  Winton,  in  which  the  gasoline 
outlet  is  opened  with  the  air  valve,  permitting  a  quantity  of  gaso- 
line to  pass  in  proportion  to  the  time  of  opening.  This  is  mixed 
with  the  air  passing  through. 

There  are  several  methods  used  for  igniting  the  charge  in  a 
gas  engine  cylinder.  Among  them  may  be  mentioned  the  gas 
jet  and  hot  tube  of  the  Otto  engines;  the  hot  head  of  the 
Hornsby-Akroyd  and  the  hot  wall  of  the  Diesel  motor.  Al- 
though vehicle  engines  of  the  Daimler  type  still  retain  the  hot 
tube  ignition,  most  of  them  operate  with  an  electric  spark. 
Electric  sparking  devices  are  of  three  general  types: 


FIG.  136.— Detail  Diagram  of  the  Valves  and  Attachments  of  a  Gas  Engine  Cylinder.  A  is 
the  inlet  port  behind  inlet  valve  held  in  its  seat  by  a  tension  spring;  B,  the  spark  plug 
for  "jump-spark'1  ignition;  C,  the  push  rod  and  compression  spring  of  the  exhaust, 
valve;  D,  the  cam  opening  the  exhaust;  E,  the  exhaust  port;  F,  the  roller  at  end  of 
valve  rod  bearing  on  the  cam,  D. 

jump  sparks,  wiping  sparks  and  break-contact  sparks. 
The  first  variety  is  usually  produced  from  a  high-ten- 
sion current — one  emerging  from  the  secondary  circuit 
of  an  induction  coil,  the  primary  circuit  being  made  and 
broken  at  timed  intervals  so  as  to  produce  a  spark  between  two 
points  in  the  secondary,  as  the  circuit  is  thus  broken.  The  two 
latter  varieties  of  spark  are  usually  produced  direct  from  the 
primary  current.  Many  authorities  consider  the  break-contact 
spark  as  a  variation  of  the  ordinary  wipe  spark,  in  which  the 
contact  has  been  so  reduced  as  to  escape  the  great  wear  occa- 
sioned by  constant  rubbing  of  metal  surfaces.  The  electric  cur- 


174 


SELF-PROPELLED   VEHICLES. 


rent  for  ignition  purposes  may  be  generated  by  ordinary  chemi- 
cal cells,  or  by  a  magneto-generator  or  small  dynamo. 

The  cylinder  is  supplied  and  exhausted  by  ports  closed 
by  poppet  or  mushroom  valves,  held  in  position  by 
springs.  The  exhaust  valve  is  positively  operated  by  cams 
geared  to  the  main  shaft ;  the  feed  valve  is  generally  operated  by 
suction  of  the  piston,  although  some  motors  have  it  also  posi- 
tively geared.  Another  important  function  in  a  gas  engine  is 
that  of  cooling  the  cylinder ;  for,  unlike  the  steam  cylinder,  which 
is  often  steam-jacketed  and  otherwise  protected  to  prevent  fall- 
ing temperature  from  checking  expansion,  the  gas  engine  cylin- 


FIG.  137.— Section  through  a  typical  Trunk  Piston  for  a  Gasoline  Engine.  Around  the  cir- 
cumference, near  the  rear  end,  are  three  circular  grooves  for  inserting  the  packing 
rings.  Through  the  central  diameter  is  a  perforation  for  admitting  the  piston  pin, 
which  is  held  in  place  by  square-headed  screws. 

The  proportions  of  the  piston  pin  must  be  carefully  calculated  for  the  load  it  is  intended 
to  bear.  In  general,  the  length  of  the  piston  pin  should  be  equal  to  that  of  the  crank 
pin,  and  its  diameter  such  as  to  bear  an  average  of  750  pounds  for  each  square  inch 
of  its  projected  area.  As  given  by  Roberts,  the  proper  diameter  of  the  pin  may  be 
determined  as  follows: 


Diameter  = 


Cylinder  area  X  M.  E.  P. 
750  X  length  of  pin. 


der  must  be  regularly  cooled,  so  as  to  be  maintained  at  a  tem- 
perature sufficiently  low  to  prevent  premature  ignition  of  the 
charge  and  consequent  disarrangement  of  the  cycle.  It  is  also 
necessary  to  avoid  such  high  degrees  as  would  cause  carboniza- 
tion of  the  lubricating  oil,  although  oils  are  produced  that  will 
give  a  fire  test  of  over  600°,  a  point  sufficiently  high  for  most 
well  designed  motors.  With  inferior  grades  of  lubricating  oil, 
and  insufficient  cylinder-cooling  devices,  the  danger  of  the  en- 
gine "grinding  itself  to  pieces"  is  generally  to  be  feared.  This 
is  one  excellent  reason,  as  stated  by  several  authorities,  why  an 


GAS  ENGINE   OPERATION. 


175 


air-cooled  cylinder  is  insufficient  for  vehicle  motors  of  more 
than  two  horse-power.  It  does  not  cool  rapidly  enough.  There 
are  two  methods  of  cylinder-cooling:  air-cooling  by  transverse, 
or  longitudinal  ribbing,  by  radiating  pins  or  by  rotary  fan;  and 
water  cooling,  by  circulation  of  water  or  other  liquid  through 
jacket  spaces  around  the  cylinder  chamber. 

The  operation  of  the  engine,  as  regards  both  speed  and 
power,  is  controlled  in  two  ways :  by  a  centrifugal  gov- 
ernor on  the  main  shaft,  or  by  a  throttling  lever  at 
the  driver's  hand.  The  mechanical  governors  are  of  two  kinds. 
In  the  first  we  have  those  operated  on  the  "hit-and-miss"  prin- 


FIG.  138.— Piston  Packing  Ring  for  a  Gas  Engine  Cylinder.  The  inner  and  outer 
circumferences  are  eccentrically  arranged,  to  as  to  permit  of  considerable 
expansion  under  heat. 

ciple,  which  involves  some  form  of  cam  and  push  rod  mechanism 
to  be  thrown  out  of  gear  at  high  speeds  and  cause  the  engine  to 
miss  charge  or  exhaust  by  opening  or  closing  the  exhaust  valve, 
or  closing  the  feed  valve  during  one  or  several  strokes.  Such  a 
variety  of  governing  mechanism  may  also  be  geared  to  open  the 
circuit  of  the  sparking  current,  thus  preventing  timed  ignition. 
The  latter  method,  however,  involves  short-circuiting  the  bat- 
tery and  is  seldom  used  where  chemical  cells  supply 
the  current.  A  second  theory  of  governor  regulation 
involves  mechanical  operation  of  a  throttle  valve,  either  for 


176 


SELF-PROPELLED  VEHICLES. 


the  pure  gasoline  supply  or  for  the  mixture  leaving  the  car- 
buretter under  piston  suction.  The  latter  of  these  is  the  prefer- 
able under  most  conditions  since,  unlike  the  former,  it  seldom 
allows  the  feeding  of  a  mixture  that  may  not  be  exploded,  as 
must  be  the  case  if  the  original  source  of  gasoline  is  throttled. 


FlO.  139.— Fly- Wheel  of  an  Engine.  Since  the  fly-wheel  of  a  gas  engine  serves  the  func- 
tion of  "  storing  up  "  energy  and  equalizing  the  conditions  of  operation,  its  propor- 
tions must  be  carefully  calculated.  As  given  by  Roberts,  the  proper  weight  for  a 
given  engine  may  be  found  as  follows: 

Weight  = I.  H.  P.  X  111,600,000,000 

(wheel    diameter)'  X   (R.  P.  M.)3  X  E 

in  which  E  is  the  co-efficient  of  permissible  unsteadiness.  The  same  authority  says 
that  the  length  of  the  hub  should  be  between  1.5  and  2.5  the  diameter  of  the  crank 
shaft;  and,  that  the  outside  diameter  of  the  wheel  should  be  between  4  and  5  times 
the  stroke  length,  which,  with  a  rim-speed  of  6,000  feet  per  minute,  which  is  the  prac- 
tical maximum,  gives  the  formula: 

1910 

Diameter  = . 

R.  P.  M. 

Here,  1910  is  the  approximate  quotient  between  6,000  and  3.14159,  or  the  ratio  between 
the  circumference  and  diameter  of  a  circle. 

Construction  of  the  Cylinder  and  Piston — The  cylinder  of 
an  internal  combustion  motor  is  open  at  the  front  and  has  the 
valves  for  admitting  and  expelling  the  fuel  at  the  rear.  The 
piston  is  always  of  the  "trunk"  pattern — a  cylindrical  box  some- 
what shorter  than  its  stroke  and  in  length  usually  about  one- 
third  more  than  its  diameter.  For  smaller  types  of  motor  the 
side  walls  of  the  piston  are  about  5-16  inch  in  thickness,  never 
less,  and  the  rear  end  wall  is,  as  a  usual  thing,  somewhat  more. 
The  cylinder  and  piston  are  machined  so  as  to  give  a  play  of 
about  .001  inch,  thus  allowing  the  piston  to  move  easily  in 
the  length  of  the  bore.  In  order  to  further  ensure  a  good  fit, 


GAS  ENGINE  OPERATION. 

three,  and  sometimes  four,  iron  rings  are  inserted  in  grooves  cut 
in  the  circumference  of  the  piston  near  the  rear  end,  and  held 
in  position  with  dowel  screws.  These  piston  rings  are  so  made 
that  the  external  and  internal  circumferences  form  eccentric 
circles,  as  shown  in  the  accompanying  figure.  They  are  also  cut 
open  at  one  point.  By  this  means  is  secured  a  play  in  the 
grooves  of  at  least  1-32  inch,  which  allows  for  expansion  and 
lengthening  of  the  rings  under  heat  of  the  ignited  fuel.  The 
rings  are  sprung  on  over  the  junk  rings  between  the  grooves, 
and  when  in  place  should  have  an  outside  diameter  which  can 
fit  the  cylinder  bore.  This  bore  is  usually  one  or  two-thou- 
sandths of  an  inch  larger  than  the  outside  diameter  of  the 
piston.  Owing  to  the  fact  that  the  heat  produced  in  an 
explosive  motor  cylinder  is  greater  than  in  a  steam  cylinder,  a 
slight  play  is  allowed  for  the  rings  at  the  sides. 

The  Crank  and  Driving  Gear. — In  the  disposition  of  the 
crank  and  driving  connections,  the  explosive  motor  differs  again 
from  the  steam  engine.  The  piston  rod  in  the  steam  engine 
slides  through  the  stuffing  box  in  the  cylinder  head,  and  the 
crank  is  attached  to  the  end  at  the  cross  head,  which  works 
between  guides.  The  gas  engine  cylinder,  being  open  at  the 
forward  end,  has  no  head  or  stuffing  box  and  no  piston  rod 
proper;  in  fact,  the  crank  and  piston  rod  are  combined  in  one. 
The  crank  is  hung  on  the  gudgeon  pin  fixed'  midway  in  the 
length  of  the  hollow  trunk  piston,  and  works  on  the  crank  shaft, 
upon  which  the  fly  wheel  is  secured.  Although,  as  we  have 
already  seen,  the  small  steam  engines  for  vehicle  use  dispense 
with  the  fly  wheel,  such  a  balance  is  positively  essential  in  a  gas 
engine  of  any  size  or  power.  The  reason  for  this  lies  in  the  fact 
that  the  ordinary  four-cycle  motor,  having  but  one  power  stroke 
in  every  two  revolutions  of  the  crank  shaft,  requires  a  heavy  fly 
wheel  to  counteract  the  speed  fluctuations  and  to  "store  up" 
energy  sufficient  to  carry  the  rotation  through  the  three  idle 
strokes  of  exhaust,  inhaust  and  compression.  For  this  reason 
gas  engine  fly  wheels  are  made  much  heavier  than  those  designed 
for  steam  engine  use.  Many  gas  and  gasoline  motors  are  also 
made  with  two  fly  wheels,  one  on  either  side  of  the  crank  pin, 
which  is  in  fact  attached  midway  on  a  radius  of  the  two  wheels, 
or  "discs,"  as  in  all  enclosed  crank  case  motors. 


CHAPTER    FIFTEEN. 

THE    PRESSURE,   TEMPERATURE    AND    VOLUME    OF    GASES    IN 

A   GAS   ENGINE. 

Operation  of  Explosive  flotors.— Since  an  explosive  motor 
operates  through  the  rapid  expansion  of  gas  under  conditions  of 
combustion,  calculations  to  determine  its  power  and  other  ca- 
pacities must  be  based  on  considerations  of  volume,  pressure  and 
temperature.  As  may  be  readily  understood,  either  of  these 
elements  may  be  taken  as  a  basis  for  calculations  including  the 
others,  since,  other  things  being  equal,  the  degree  of  temperature 
produces  the  volume,  or  the  relative  tendency  to  expansion,  and 
the  increase  of  volume  to  a  certain  point  involves  increase  of 
pressure.  Thus  it  follows  that  the  whole  cycle  of  a  gas  engine  is 
characterized  by  a  proportionate  increase,  the  factors  of  variation 
being  considered,  in  the  elements  productive  of  power  and 
motion.  At  the  aspirating,  or  inhaust,  stroke,  the  outward  move- 
ment of  the  piston,  by  creating  a  partial  vacuum,  causes  the  feed 
valves  to  open  under  atmospheric  pressure,  thus  indicating  that 
the  pressure  within  is  lower  than  that  of  the  atmosphere  without. 
At  explosion  the  volume  and  temperature  are  raised,  and  at  the 
end  of  the  scavenging  stroke,  the  exhausted  products  of  com- 
bustion are  expelled  with  a  force  indicative  of  a  pressure  several 
times  greater  than  the  atmosphere.  The  inhaust  stroke  being 
completed,  and  the  feed  valves  closed  by  force  of  a  spring,  there 
is  no  considerable  increase  in  volume  and  pressure  due  to  con- 
tact with  the  hot  cylinder  walls,  nor  yet  from  the  residuum  of 
burnt  products  in  the  clearance  or  combustion  chamber, 
although,  owing  to  the  valve  spring,  the  pressure  of  the  con- 
tained gases  is  below  one  atmosphere.  As  shown  by  average 
indicator  tracings,  the  rise  in  pressure  during  the  inhaust  stroke 
is  from  a  negative  point  to  generally  about  13.50  pounds  to  the 
square  inch.  So  soon,  however,  as  the  compression  stroke 
begins,  the  indicator  tracing  shows  a  steady  rise  from  14.7 
pounds  to  the  square  inch,  or  normal  atmospheric  pressure,  to 
65  or  70  pounds  at  the  completion  of  the  stroke,  the  rise  in  tem- 
perature being  on  an  increasing  ratio  during  the  latter  half, 

178 


PRESSURE,   TEMPERATURE  AND   VOLUME. 

although  during  the  first  half  approximately  regular.  That  the 
superheated  residua  of  combustion  in  the  clearance,  being  again 
compressed,  are  effective  in  producing  the  rapid  rise  at  the  end 
of  the  stroke  is  suggested  by  the  fact  that  the  figures  for  both 
pressure  and  temperature  are,  other  things  equal,  greater  for  a 
non-scavenging  than  for  a  scavenging  engine.  At  the  end  of  the 
compression  stroke  the  gas  mixture  in  cylinder  has  attained  its 
greatest  density,  also  its  greatest  pressure  and  temperature  pre- 
vious to  combustion.  It  is  then  ready  for  firing,  which  is  accom- 
plished very  shortly  before  the  piston  begins  the  second  out- 
stroke,  the  explosion  serving  to  bring  the  gas  to  the  maximum 
point  for  volume,,  pressure  and  temperature  alike.  In  fact,  the 
effect,  as  shown  by  thermometer  and  indicator  tests,  is  that  the 
temperature  in  a  gas  engine  cylinder  rises  during  this  stroke 
from  between  500  and  700  degrees,  absolute,  as  noted  when  the 
engine  is  running  at  good  speed,  to  between  1,500  and  2,000 
degrees,  on  the  average,  and  the  pressure  from  an  indicated  65 
or  70  pounds  to  200  or  230  pounds  per  square  inch.  The  fall  in 
both  particulars  is  equally  rapid  during  the  succeeding  in-stroke, 
when  the  burnt  gases,  under  impulse  from  the  piston,  are  ex- 
pelled through  the  open  valves.  At  the  completion  of  this  ex- 
haust stroke,  accordingly,  the  same  cycle  of  pressure  and  tem- 
perature transitions  is  begun  again,  all  superfluous  heat  units 
having  been  carried  off  in  the  exhaust  and  through  the  cylinder- 
cooling  system. 

Regarding  the  time  of  firing  practice  differs  considerably. 
Generally,  as  stated  above,  it  is  slightly  before  the  beginning  of 
the  power  stroke,  in  order  to  allow  time  for  the  burning  gas  to 
begin  expansion.  Slow-speed  motors  are  generally  fired  very 
slightly  after  the  dead  centre.  With  high-speed  motors  it  varies 
from  about  5  degrees  after  dead  centre  to  30  or  40  degrees 
ahead  (as  measured  on  the  crank).  With  a  large  spark,  hot 
motor  and  well-mixed  fuel,  the  advanced  spark  is  seldom  set 
more  than  15  or  20  degrees  ahead. 

Principles  of  Pressure  and  Temperature  in  Oases. — As  we 

have  already  explained  in  the  section  on  steam  engines,  a  leading 
property  of  gases  is  that,  the  temperature  remaining  about  the 
same,  an  increase  in  volume  involves  a  corresponding  decrease 
in  pressure,  and,  that  to  maintain  even  a  constant  pressure  in  an 


ISO 


SELF-PROPELLED    VEHICLES. 


expanding  gas,  the  temperature  jnust  be  raised  on  a  steadily 
increasing  ratio.  In  other  words  a  given  cubic  content  of  ex- 
panding gas,  at  a  constant  temperature,  shows  a  lower  pressure 
per  square  inch  as  the  expansion  progresses,  and,  in  order  to 
obtain  a  given  total,  original,  efficient  pressure  the  cubic  content 
of  the  cylinder  must  increase  with  the  expansion.  On  the  other 
hand,  if  a  given  cubic  content  of  gas  be  compressed  to  half  its 
normal  volume,  without  involving  an  accompanying  increase  in 


FIG.  140.— The  Parts  of  an  Air-Cooled  Vehicle  Motor,  shown  for  an  efficient  make  of 
bicycle  gasoline  engine.  The  cylinder,  carrying  radiating  ribs,  is  shown  at  the  left. 
Next  is  the  outside  view  of  one-half  of  the  crank  case;  then  the  trunk  piston  with  the 
piston  rod  attached  to  the  crank  discs.  At  the  right  of  the  cut  is  the  inside  view  of 
the  other  half  of  the  crank  case,  with  the  cylinder  head  lying  in  front  of  it.  The 
crank  disc,  or  fly  wheel,  shows  the  double  eccentric  cam  groove  for  operating  the  ex- 
haust valve  rod,  which  was  a  distinctive  feature  of  the  earlier  Daimler  gasoline 
engines. 


temperature,  the  pressure  is  doubled.  In  either  case,  an  undue 
increase  of  temperature  operates  to  neutralize  the  stated  prin- 
ciple. 

Fom  these  facts  we  may  deduce  the  principles  that : 

1.  The  pressure  of  a  gas  varies  inversely  with  the  volume  and 
directly  with  the  temperature. 

2.  The  volume  of  a  gas  varies  inversely  with  the  pressure  and 
directly  with  the  temperature. 


PRESSURE,    TEMPERATURE  AND   VOLUME. 

3.  The  temperature  of  a  gas  varies  directly  with  both  the 
pressure  and  the  volume. 

To  state  these  principles  in  another  way,  we  may  say : 

1.  An  increased  pressure  involves  a  decreased  volume  or  an 
increased  temperature. 

2.  An  increased  volume  involves  a  decreased  pressure  or  an 
increased  temperature. 

3.  An  increased  temperature  involves  an  increased  volume  and 
an  increased  pressure. 

As  the  operative  conditions  in  a  gas  engine  are  immensely 
irregular  no  formulae  can  precisely  express  the  proper  tem- 
perature, volume  or  pressure  for  theoretical  situations.  Since, 
however,  the  attributes  of  the  fuel  gas  at  various  points  in  the 
cycle  series  are  in  direct  proportion  to  the  dimensions  of  the 
cylinder,  the  length  of  the  stroke,  the  cubic  content  of  the  clear- 
ance, and  the  percentage  of  atmospheric  air  in  the  explosive 
mixture,  very  exact  figures  may  be  found  to  express  the  power 
and  capacity  of  any  particular  engine. 

Proportionate  Figures  for  Temperature  and   Pressure — In 

the  operation  of  the  explosive  motor  the  fuel  gas  is  confined 
within  the  cylinder,  so  long  as  its  properties  are  significant  in 
calculation  on  power  and  speed.  The  figures  for  the  total  cylin- 
der content  being  then  determined,  we  have  a  constant  standard 
of  comparison  for  calculating  the  pressure  and  temperature  of  a 
given  mixture  of  gas  and  air  under  the  several  cycular  conditions. 
For,  although  the  contained  gas  ocupies  the  same  cubic  content 
at  the  beginning  of  the  compression  stroke  and  at  the  end  of  the 
firing  stroke,  it  is  obvious  that  its  proper  volume  is  vastly  in- 
creased at  the  latter  moment,  as  indicated  by  the  raised  pressure 
and  temperature  figures.  But,  following  the  principles  laid  down 
above,  we  find  that  the  figures  are  regular  and  proportionate  as 
between  the  initial  and  final  volumes,  pressures  and  temperatures. 

The  following  formulae  express  these  conditions : 

Let  P'    be  the  initial  pressure. 

Let  P"  be  the  final  pressure. 

Let  T'    be  the  initial  temperature. 

Let  T''  be  the  final  temperature. 

Let  V    be  the  initial  volume. 

Let  V"  be  the  final  volume. 


182  SELF-PROPELLED    VEHICLES. 

Then  :— 

P'     V'     _     v//.          F   V' 

—  V         > 


P"  V" 

F  T"     _     p/;.          T-   P"     =     T|I 

From  these  formulae  we  may  deduce  the  obvious  rules  that : 

1.  The  final  volume  divided  by  the  initial  volume  is  equal  to 
the  final  pressure  divided  by  the  initial  pressure;  or,  the  final 
volume  divided  by  the  initial  pressure  is  equal  to  the  initial 
volume  divided  by  the  final  pressure.    Having  reduced  this  to  a 
definite  basis  we  have  it  that  the  final  volume  equals  the  quotient 
found  by  dividing  the  product  of  the  initial  pressure  and  initial 
volume  by  the  final  pressure. 

2.  On   precisely   similar  lines,   the  final   pressure   equals   the 
quotient  found  by  dividing  the  product  of  the  initial  pressure 
and  initial  volume  by  the  final  volume. 

3.  The    final    pressure    also    equals    the    quotient    found    by 
dividing  the  product  of  the  initial  pressure  and  final  temperature 
by  the  initial  temperature. 

4.  The  final  temperature  equals  the  quotient  found  by  dividing 
the  product  of  the  initial  temperature  and  final  pressure  by  the 
initial  pressure. 

In  calculating  practical  figures  the  initial  volume,  pressure 
and  temperature  may  be  those  taken  at  the  beginning  of  the  com- 
pression stroke,  when  the  figure  for  volume  is  at  the  highest 
point  and  the  figures  for  pressure  and  temperature  are  at  the 
lowest  points,  independent  of  any  external  agency  that  can  mod- 
ify them.  The  formulae  given  above  may  be  used  for  calculating 
between  the  initial  point  and  any  subsequently  following  by  com- 
paring its  figures  with  the  figures  found  at  that  given  point.  In 
practice,  however,  they  are  always  used  in  connection  with  the 
absolute  figures  for  pressure  and  temperature,  next  to  be  de- 
scribed. 

Absolute   Figures  for   Pressure   and   Temperature — As    is 

obvious,  the  proportions  of  the  cylinder  content,  stroke  and  clear- 
ance are  always  constant  and  known.  Those  for  temperature  may 
be  found  on  the  thermometer  scale:  those  for  pressure,  by  the 
indicator  gauge.  In  practice,  however,  it  is  customary  to  use  "ab- 


PRESSURE,    TEMPERATURE  AND   VOLUME. 


183 


solute  figures,"  as  they  are  called,  which  represent  the  sum  of  the 
thermometric  or  the  gauge  figures  with  certain  constants  deter- 
mined by  calculation  and  experience.  Thus  the  absolute  pressure 
is  the  gauge  pressure  plus  14.7,  which  is  the  atmospheric  press- 
ure in  pounds  per  square  inch.  The  absolute  temperature  is  the 


TIG.  14L— A  Daimler  Single-Cylinder  Motor  Intended  for  Stationary  Use.    Attached  to 
the  head  of  the  water-cooled  cylinder  are  the  gasoline  chamber  and  carbu 
The  lubricating  cup  is  shown  immediately  below.    The  exhaust  valve,  not  shown,  is 
operated  by  a  cam  on  the  secondary  shaft,  geared  to  the  crank  shaft,  as  may  be  seen 
within  the  fly-wheel.    In  essential  particulars  this  motor  is  identical  with  those 
for  vehicle  propulsion;  the  method  of  mounting  being,  of  course,  different. 

sum  of  the  sensible  thermometric  temperature  and  the  constant 
461.  This  latter  figure,  which  is  properly  expressed  as  460.66. 
represents  the  total  number  of  degrees  on  the  Fahrenheit  scale 
from  32°  below  the  freezing  point  of  water  to  the  absolute  zero 
of  temperature,  as  calculated  by  the  expansion  ratio  of  gases. 


184  SELF-PROPELLED    VEHICLES. 

Thus,  in  calculating  temperatures  in  gas  engine  practice,  the  cus- 
tom is  to  count  from  absolute  zero.  For  example,  instead  of 
64°,  writing  525°,  and  instead  of  32°,  writing  493°,  or,  more  cor- 
rectly, 492.66°.  The  utility  of  this  system  lies  in  the  fact  that,  as 
a  gas  has  been  found  to  expand  by  1-273  of  its  original  volume 
for  each  degree,  centigrade,  or  by  1-461  for  each  degree,  Fahren- 
heit, of  increased  temperature,  we  have  by  the  use  of  absolute 
figures  an  opproximate  expression  for  both  increased  heat  and 
increased  volume  in  the  same  number. 

On  a  scale  giving  as  a  unit  one  part  out  of  493  for  32°,  and  one 
part  out  of  525  for  64°,  we  have  a  co-efficient  of  expansion  that 
is  capable  of  ready  verification.  The  same  line  of  reasoning  holds 
good  for  pressure  calculations,  which  start  from  a  theoretical 
zero  at  the  beginning  of  the  inhaust  stroke,  and  are,  theoretically, 
reducible  to  atmospheric  conditions  only  by  the  addition  of  the 
14.7  pounds  per  square  inch.  For  this  reason  tables  giving  the 
pressure  series  for  gas  cylinders  of  various  proportions  at  the 
end  of  the  compression  stroke  most  often  start  from  the  theoreti- 
cal one  pound  pressure  per  square  inch,  which  column  gives  the 
figures  to  be  multiplied  by  the  ascertained  pressures  at  the  begin- 
ning of  the  compression  stroke  for  any  given  motor. 

fleasuring  the  Conditions  of  Operation.; — The  factors  enter- 
ing to  vary  the  figures,  with  the  same  initial  pressures  in  different 
engines,  are  the  ratio  of  compression  and  the  percentage  of  the 
clearance  volume,  as  compared  with  the  total  cylinder  volume. 
The  ratio  of  compression  is  found  to  be  equal  to  the  quotient  of 
the  total  volume  of  the  cylinder  from  the  beginning  to  the  end 
of  the  stroke,  including  also  the  clearance,  divided  by  the  volume 
of  the  clearance,  which,  as  is  evident,  is  never  decreased  during 
any  portion  of  a  stroke.  The  percentage  of  the  clearance  volume 
is  similarly  found  by  dividing  the  volume  of  the  clearance  by 
the  volume  of  the  piston  displacement :  in  other  words,  it  is  the 
quotient  of  the  cubic  content  of  the  clearance,  from  the  rear  of 
the  cylinder  to  the  rearmost  reach  of  the  piston  at  the  end  of  an 
in-stroke,  divided  by  the  cubic  content  of  that  portion  of  the 
cylinder  included  between  the  inmost  point  of  the  in-stroke  and 
the  outmost  point  of  the  out-stroke,  as  indicated  bv  the  position 
of  the  rear  end  of  the  piston  at  those  two  points.  Having  ascer- 
tained these  proportions  for  any  given  engine  the  absolute  figures 


PRESSURE,    TEMPERATURE  AND   VOLUME. 


185 


for  operating  pressure  and  temperature  may  be  readily  found. 
Thus,  in  order  to  find  the  pressure  per  square  inch  at  the  end  of 
the  compression  stroke,  it  is  necessary  only  to  multiply  the  figure 
corresponding  to  an  engine  with  the  given  compression  ratio  and 
percentage  of  clearance  by  the  ascertained  gauge  pressure  at  the 
beginning  of  the  stroke,  or  any  other  required  pressure  at  the 
same  point.  Thus  the  initial  pressure  at  theoretical  unity  for  a 
cylinder  having  a  compression  ratio  of  3  and  a  clearance  per- 
centage of  50  is  4407,  which  multiplied  by  13,  the  gauge  or 
desired  pressure,  gives  57.29;  by  13.2,  gives  58.17;  by  13.5,  gives 
59.49;  by  14,  gives  61.69;  by  14.7,  gives  64.78. 


15  TeetK 


1 


FIG.  142.— Rear  and  Side  Elevation  of  a  De  Dion  Water-Cooled  Carriage  Motor,  showing 
method  of  joining  the  two  halves  of  the  crank  case  and  bolting  them  to  the  cylinder. 
As  indicated,  also,  the  water-jackets,  cylinder  head  and  valve  chamber  are  cast  inte- 
gral  with  the  cylinder. 

The  compression  temperature  is  similarly  determined  by  multi- 
plying the  found  or  required  absolute  temperature  at  the  begin- 
ning of  the  stroke  by  the  figure  for  one  degree  for  a  type  of 
engine  having  the  same  compression  ratio  as  the  one  in  ques- 
tion. Thus,  for  an  engine  having  the  ratio  at  3,  the  theoretical 
initial  temperature  is  estimated  as  1.46°,  whicli,  for  an  initial 
absolute  temperature  of  525°  gives  766°,  and  for  560°  gives  822°. 

Since  these  processes  are  of  importance  in  calculating  the 
power  of  a  gas  engine,  it  is  well  to  enter  into  the  general  prin- 
ciples involved,  as  introductory  to  a  more  extended  study  of  the 
subject.  The  cubic  content  of  a  cylinder,  together  with  the  con- 


186  SELF-PROPELLED    VEHICLES. 

tent  of  the  stroke  and  clearance  areas  may,  of  course,  be  cal- 
culated by  knowing  the  diameter  and  length  of  the  cylinder  and 
the  length  of  the  stroke.  A  more  practical  method  for  unskilled 
mathematicians  and  mechanicians  is  that  suggested  by  E.  W. 
Roberts  in  his  "Gas  Engine  Handbook."  As  described  by  him 
the  process  is,  briefly,  to  turn  the  crank  to  a  dead  center  and  close 
the  valves,  and  then  fill  the  cylinder  with  water.  By  altering  the 
position  of  the  piston  rod  from  in-stroke  end  to  out-stroke  end, 
the  cubic  content  of  both  clearance  and  total  cylinder  may  be 
accurately  estimated.  The  water  having  been  weighed  before 
pouring  it  into  the  cylinder,  the  weight  of  that  left  over  is  a 
ready  indication  of  the  weight  of  that  within.  Now,  as  is  well 
known,  water  at  a  temperature  of  39.1°  weighs  62.5  pounds  per 
cubic  foot.  Thus,  when  the  temperature  of  the  water  is  higher 
than  39.1°  its  weight  per  cubic  foot  may  be  found  by  the  follow- 
ing formula,  in  which  T  is  the  thermometric  temperature,  461, 
the  constant  of  absolute  temperature,  and  500,  the  absolute  tem- 
perature of  water  at  39.1°. 

62.5  x  2 


T  -f  461    ,  500         =    Weight  per  cubic  foot. 

500  "    T  -f  461 

This  formula  is  particularly  convenient  where  the  cylinder  has 
a  spherical  or  enlarged  combustion  chamber,  which  would  in- 
volve mathematical  processes  of  considerable  intricacy  to  prop- 
erly estimate  its  content.  As  it  is,  the  only  requirement  is  that 
we  substitute  the  ascertained  temperature  figures  for  T  wherever 
it  occurs ;  reduce  the  factions  to  a  common  denominator,  and 
perform  the  indicated  additions  and  divisions. 

Application  of  the  Formulae. — Taking  the  fuel  gas  at  con- 
stant volume — this  is  theoretically  the  condition  in  the  gas 
engine — and  raising  its  temperature  through  a  certain  number  of 
degrees  involves  a  proportionate  increase  in  pressure.  Thus, 
knowing  the  initial  and  final  temperatures,  we  may  derive  the 
gauge  pressure  of  compression,  since  the  pressure  of  a  gas  is  in 
direct  ratio  to  the  temperature.  If  from  an  absolute  initial  tem- 
perature of  525°  (64°  plus  461)  we  have  a  final  temperature  of 
2161°  (1700°  plus  461),  the  increase  or  acquired  temperature  is 
1636°.  Beginning  at  525°,  the  ratio  of  increasing  volume  and 


PRESSURE,   TEMPERATURE  AND   VOLUME.  187 

temperature  is  i-525th,  or  .0019047.  Then,  multiplying  together 
the  ratio  thus  found,  the  acquired  temperature  and  the  absolute, 
initial  pressure  (14.7),  we  have  the  gauge  pressure  of  compres- 
sion, which  is  45.80  pounds  to  the  square  inch.  As  may  be  read- 
ily demonstrated  by  performing  the  same  operations  with  other 
initial  and  final  figures,  the  initial  presure  is  in  strict  proportion 
to  the  volume  and  temperature.  Other  things  being  equal,  there- 
fore, it  might  seem  reasonable  to  lay  down  the  rule  that,  the 
higher  the  pressure  of  compression,  the  greater  the  rise  in  tem- 
perature at  the  point  of  ignition  and,  consequently,  the  greater 
the  efficiency  in  units  of  work.  Accordingly,  we  find  that,  while 
in  many  early  'gas  engines  this  pressure  was  very  much  below 
fifty  pounds  to  the  square  inch,  with  the  more  modern  and  im- 
proved patterns  it  strikes  an  average  in  the  neighborhood  of 
seventy  pounds.  It  must  not  be  forgotten,  however,  that  this 
rule  has  very  definite  limitations,  and  that  beyond  a  certain  point 
of  increased  compression  pressure  the  efficiency  ratio  begins  to 
decrease  rapidly.  As  has  been  already  suggested,  the  ratio  of 
compression  is  to  be  calculated  on  the  proportions  existing  be- 
tween the  clearance,  or  combustion  chamber,  and  the  total  effec- 
tive length  of  the  cylinder,  as  shown  by  the  area  of  the  piston 
sweep,  or  stroke.  Consequently  a  decrease  in  the  clearance  con- 
tent involves,  to  a  certain  point,  a  proportionate  increase  in  the 
ratio  of  compression,  with  commensurately  higher  temperature 
and  efficiency.  Thus,  applying  the  rule  for  calculating  the  com- 
pression ratios  of  two  cylinders,  in  which  the  clearance  and  total 
content  are  in  proportion  of  2  to  4  and  I  to  4,  respectively,  we 
derive  the  following  expressions : 

2  +  4     _     3  1   +  4     =     5 

Such  a  result  may  come  either  from  decreasing  the  clearance, 
increasing  the  stroke  sweep,  or  varying  the  figures  in  both  par- 
ticulars. 

Taking  a  theoretical  one  pound  pressure  and  one  degree  tem- 
perature, initial,  we  have  the  following  figures  for  varying  com- 
pression ratios  in  non-scavenging  engines,  derived  as  above : 

With  a  ratio  of  3,  we  have  4.407  for  pressure  and  1.4689  for 
temperature;  with  4,  we  have  6.498  and  1.6245,  respectively;  with 
5,  we  have  8.783  and  1.7564;  with  6,  in  the  same  way,  11.233  and 


188  SELF-PROPELLED    VEHICLES. 

1.8722.  These  figures,  multiplied  by  the  ascertained  initial  press- 
ure and  temperature  in  any  particular  engine  of  the  same  ratio, 
will  give  the  proper  figures  for  that  engine.  Fractional  figures 
range  between  those  given.  In  a  scavenging  engine — one  that 
is  constructed  to  expel  the  whole  of  the  burned  products, 
although  never  fully  accomplishing  the  result  in  practice — the 
clearance  ratio  is  virtually  an  expression  for  the  total  cubic  con- 
tent swept  by  the  piston.  Since,  then,  the  stroke-sweep  of  an 
engine  is  the  one  consideration,  as  compared  with  engines  of  dif- 
ferent proportions  in  this  particular,  we  should  have,  theoreti- 
cally, about  the  same  degree  of  pressure  and  temperature  as  are 
given  above.  As  estimated  by  several  authorities,  however,  the 
figures  vary  somewhat.  Thus,  as  before,  for  scavenging  engines 
at  the  theoretical  unity  for  initial  pressure  and  temperature,  with 
a  ratio  of  3,  we  have  4.264  for  compression  pressure,  and  1.4213 
for  compression  temperature;  for  4,  we  have  6.233  and  1.5707, 
respectively;  for  5,  we  have  8.368  and  1.6737;  an<^  f°r  6,  we  have 
10.646  and  1.7742.  The  figures  seemingly  indicate  a  difference 
of  rise  in  temperature  and  pressure  due  to  the  recompression  of 
burned  gases  that  is  about  .2  degree  for  a  compression  ratio  of 
3,  and  .1  degree  for  a  compression  ratio  of  6,  as  found  in  the 
former  type  of  engine  over  the  latter.  If  this  conclusion  is  cor- 
rect, as  some  authorities  seem  to  question,  we  find  that  the  heat 
efficiency  of  the  burned  gases,  as  found  at  the  end  of  the  com- 
pression stroke,  is  in  inverse  proportion  to  the  length  of  the 
stroke  in  any  given  engine,  indicating  the  greater  loss  of  heat 
units  to  the  jacket  water  of  the  cylinder  in  the  motor  of  pro- 
portionately longer  stroke.  Since,  then,  the  quantity  of  burned 
and  expanding  products  is  naturally  smaller  in  the  scavenging 
cylinder  than  in  one  of  the  other  type,  we  can  readily  under- 
stand how  that  the  figures  for  compression  pressure  and  tem- 
perature are  higher  for  the  latter  than  for  the  former,  as  pos- 
sessing an  absolutely  greater  internal  efficiency  for  heat  and 
pressure. 

Figures  on  Compression  Pressure. — On  the  matter  of  com- 
pression figures  this  quotation  from  Hiscox  will  suffice: 

"It  has  been  shown  that  an  ideal  efficiency  of  33  per  cent,  for 
38  pounds  compression  will  increase  to  40  per  cent,  for  66 
pounds,  and  43  per  cent,  for  88  pounds  compression.  On  the 


PRESSURE,   TEMPERATURE  AND    VOLUME. 


189 


other  hand,  greater  compression  means  greater  explosive  press- 
ure and  greater  strain  on  the  engine  structure,  which  in  future 
practice  will  probably  retain  the  compression  between  the  limits 
of  40  and  60  pounds. 

"In  experiments  made  by  Dugald  Clerk  with  a  combustion 
chamber  equal  to  0.6  of  the  space  swept  by  the  piston,  with  a 
compression  of  38  pounds,  the  consumption  of  gas  was  24  cubic 


FIG.   H2a.-The   Knox  Single-Cylinder   Runabout.    A  typical  American   gasoline 

carriage. 

feet  per  indicated  horse-power  per  hour.  With  0.4  compression 
space  and  61  pounds  compression,  the  consumption  of  gas  was 
20  cubic  feet  per  indicated  horse-power  per  hour ;  and  with  0.34 
compression  space  and  87  pounds  compression,  the  consump- 
tion of  gas  fell  to  14.8  cubic  feet  per  indicated  horse-power  per 
hour— the  actual  efficiencies  being  respectively  17.21  and  25  per 
cent.  This  was  with  a  Crossley  four-cycle  engine." 


CHAPTER    SIXTEEN. 

THE   METHODS   AND   CONDITIONS   OF   GAS    ENGINE    CYLINDER 

COOLING. 

Rate  of  Gas  Consumption. — As  given  by  several  authorities, 
who  base  their  calculations  upon  engines  possessing  the  most 
favorable  conditions  in  the  respects  above  enumerated,  and  using 
the  fuel  best  suited  to  the  end  in  view,  the  average  of  gas  con- 
sumption per  horse-power  per  hour  is  20  cubic  feet,  although,  as 
may  be  readily  understood,  such  figures  vary  with  the  kind  and 
quality  of  fuel  and  the  proportions  in  such  matters  as  are  men- 
tioned by  Hiscox,  as  above  quoted.  There  are,  however,  other 
considerations  entering  into  the  judgment  of  ideal  efficiency  and 
some  of  these  we  will  proceed  to  treat. 

The  Conditions  of  Efficiency — The  efficient  power  of  a  gas 
engine  is  not  a  matter  dependent  wholly,  or  even  largely,  on 
relative  proportions  among  any  of  the  working  parts,  and,  at 
most,  the  figures  given  above  are  averages  for  the  best  obtain- 
able conditions.  Such  favorable  conditions  consist  very  largely 
in  such  economy  as  may  be  obtained  by  keeping  the  jacket 
water  at  proper  temperature — the  higher  temperatures  at  a  few 
degrees  below  the  boiling  point  seem  best  calculated  to  prevent 
over-absorption  of  heat  units  at  every  stage  of  the  cycle — and  to 
such  as  may  be  obtained  by  securing  fuel  mixtures  and  condi- 
tions favorable  to  rapid  ignition.  Bearing  in  mind  these  elements 
of  variation  in  our  estimates  on  power,  we  may  readily  under- 
stand that  the  efficiency  of  a  gas  engine  is  expressed  by  "the 
ratio  of  heat  units  turned  into  work,  as  compared  with  the  total 
heat  produced  by  combustion/'  By  far  the  greater  proportion 
of  gas  engines — those  employed  alike  for  general  power  purposes 
and  in  propelling  motor  vehicles — have  water-cooled  cylinders ; 
the  water  for  this  purpose  being  admitted  to  a  jacket  or  water 
space  cast  around  the  cylinder's  circumference,  and  circulating 
between  that  space  and  the  feed-tank  or  cistern,  in  accordance 
with  the  laws  of  liquids,  which  cause  the  heated  layers  to  rise 
from  the  bottom  to  the  top  of  the  reservoir,  and  the  cooler  layers 

190 


CYLINDER   COOLING  DEVICES.  191 

to  fall  correspondingly.  As  stated  above,  the  foremost  utility 
subserved  by  this  arrangement  is  that  the  temperature  of  the 
cylinder  is  normally  maintained  below  the  point  at  which 
the  lubricating  oil  will  otherwise  carbonize.  Further- 
more, the  walls  would  also  become  so  heated  that 
the  fuel  charge  would  be  fired  out  of  time>  with  the 
result  of  disarranging  the  cycle  and  rendering  the  en- 
gine inefficient.  That  this  result  would  follow  is  prac- 
tically demonstrated  in  engines  of  the  Hornsby-Akroyd  type, 
wherein,  instead  of  any  spark,  tube  or  other  timed  devices  to  fire 
the  charge  after  the  cylinder  has  fairly  taken  up  its  cycle,  the 
heated  walls  of  the  combustion  chamber  provide  the  necessary 
temperature  under  cycular  conditions.  This  combustion  cham- 
ber is  unjacketed  and  connected  to  the  jacketed  cylinder  cham- 
ber by  a  passage  of  small  diameter,  so  that  only  a  minute  portion 
of  the  contents  of  either  will  mix  freely,  except  under  compres- 
sion. During  the  aspirating  stroke  of  the  piston  the  gas  mixture 
is  fed  into  this  unjacketed  chamber,  and  the  air  into  the  cylinder 
space,  with  the  result  that,  no  portion  of  its  heat  being  absorbed 
by  jacket  water,  the  temperature  is  raised  to  the  firing  point  of 
the  fuel  by  the  mixture  of  air  under  the  added  pressure  of  the 
compression  stroke.  This  result  generally  follows  after  the  firing 
of  one  charge  by  external  means  of  raising  the  temperature,  and 
is  to  be  attributed  most  largely  to  the  absence  of  the  water- 
jacket.  Thus,  although  the  "cooling  system"  is  a  positive  neces- 
sity in  the  space  swept  by  the  piston,  for  the  reasons  above 
stated,  it  forms  a  serious  consideration  in  estimates  on  efficiency 
by  absorbing  a  large  proportion  of  the  heat  units  generated  by 
ignition  of  the  fuel,  and  thus,  under  any  conditions  operating  to 
reduce  the  total  efficiency,  even  though  by  only  a  fractional  ratio. 

Jacket  Water :  Its  Rate  and  Quantity. — On  this  point  His- 
cox  makes  an  interesting  statement  on  the  proportions  of  ab- 
sorbed and  efficient  heat  units,  as  estimated  under  typical  condi- 
tions. He  says : 

"In  regard  to  the  actual  consumption  of  water  per  horse- 
power and  the  amount  of  heat  carried  off  by  it,  the  study  of  Eng- 
lish trials  of  an  Atkinson,  a  Crossley,  and  a  Griffin  engine  showed 
62  pounds  of  water  per  indicated  horse-power  per  hour,  with  a 
rise  in  temperature  of  50°  F.,  or  3,100  heat  units  carried  off  in  the 


102 


SELF-PROPELLED    VEHICLES. 


water  out  of  12,027  theoretical  heat  units  that  were  fed  to  the 
motor  through  the  19  cubic  feet  of  gas  at  633  heat  units  per 
cubic  foot  per  hour. 

"Theoretically,  2,564  heat  units  per  hour  is  equal  to  one  horse- 
power. Then,  0.257  of  the  total  was  given  to  the  jacket  water, 
0.213  to  the  indicated  power,  and  the  balance,  53  per  cent.,  went 
to  the  exhaust,  radiation  and  the  reheating  of  the  previous  charge 
in  the  clearance  and  in  expanding  the  nitrogen  of  the  air.  *  * 

"In  a  trial  with  a  Crossley  engine,  42  pounds  of  water  per 
horse-power  per  hour  were  passed  through  the  cylinder  jacket, 
with  a  rise  in  temperature  of  128°  F. — equal  to  5,376  heat  units 


FIG.  143.— Sectional  View  of  the  Water  Jackets  and  Water  Circulation  Connections  of  a 
Gas  Engine  Cylinder,  in  which  the  circulation  operates  through  gravity.  The  arrows 
indicate  direction  of  circulation  current. 

to  the  water  from  12,833  neat  units  fed  to  the  engine  through  20.5 
cubic  feet  of  gas  at  626  heat  units  per  cubic  foot. 

********** 
"An  experimental  test  of  the  performance  of  a  gas  engine 
below  its  maximum  load  has  shown  a  large  increase  in  the  con- 
sumption of  gas  per  actual  horse-power,  with  a  decrease  of  load, 
as  the  following  figures  from  observed  trials  show:  An  actual  12 
H.  P.  engine  at  full  load  used  15  cubic  feet  of  gas  per  horse- 
power per  hour;  at  10  H.  P.,  15^  cubic  feet ;  at  8  H.  P.,  i6J  cubic 
feet ;  at  6  H.  P.,  18  cubic  feet ;  at  4  H.  P.,  21  cubic  feet ;  at  2  H.  P., 
30  cubic  feet  of  gas  per  actual  horse-power  per  hour.  This  in- 
dicates an  economy  gained  in  gauging  the  size  of  a  gas  engine  to 
the  actual  power  required,  in  consideration  of  the  fact  that  the 


CYLINDER   COOLING  DEVICES.  193 

engine  friction  and  gas  consumption  for  ignition  are  constants 
for  all  or  any  power  actually  given  out  by  the  engine." 

Gas  Consumption  and  Power  Efficiency. — Such  facts  bring 
us  to  an  interesting  situation  in  regard  to  estimating  for  the 
highest  power-efficiency  in  a  gas  engine.  As  has  already  been 
stated,  an  increase  in  compression,  involving  a  smaller  com- 
bustion chamber  or  a  longer  stroke,  ensures  a  higher  temperature 
and  explosive  force  at  ignition.  But,  in  obtaining  these  ends  by 
such  relatively  longer  piston-sweep,  we  are  met  by  the  difficulty 
incident  upon  exposing  the  ignited  gas  to  a  commensurately 
larger  area  of  heat-absorption  through  the  circulating  jacket- 
water.  As  it  is  impracticable  to  leave  any  portion  of  the  sweep 
space  unjacketed,  it  is  obvious  that  economy  in  this  respect  must 
be  obtained  by  some  mechanical  or  physical  variation  in  the  con- 


FlG.  144.— Section  through  a  Gas  Engine  Cylinder  having  a  spherical  clearance  and  a 
spherical  depression  on  the  piston  head.  The  shaded  sections  at  top  and  bottom  indi- 
cate the  water  jackets. 

ditions.  Thus,  for  example,  considerable  economy  in  fuel-con- 
sumption may  be  obtained  by  increasing  the  speed  of  the  engine, 
which,  when  the  cycle  is  well  established,  involves  that  the  explo- 
sive impulses  succeed  one  another  so  rapidly  that  the  percentage 
of  heat  units  absorbed  by  the  jacket  water  is  constantly  reduced. 
This  fact  is  shown  by  the  data  above  quoted  for  a  12  H.  P.  engine, 
driven  successively  at  10,  8,  6,  4  and  2  H.  P.  and  showing  an 
increase  in  gas-consumption  per  horse-power  in  inverse  ratio  to 
the  effective  power-output.  Such  a  reduction  of  power-output 
involves,  of  course,  a  lower  speed,  and  is  accomplished  by  reg- 
ulating the  gas  and  air  supply.  But  if,  according  to  the  figures 
quoted  above,  a  12  H.  P.  engine  at  full  power  consumes  15  cubic 
feet  of  gas  per  horse-power  per  hour,  which  is  180  cubic  feet  per 


194  SELF-PROPELLED    VEHICLES. 

hour,  it  will  at  10  horse-power  consume  155  cubic  feet,  or  86  per 
cent. ;  at  8  horse-power,  132  cubic  feet,  or  75  per  cent. ;  at  6  horse- 
power, 108  cubic  feet,  or  60  per  cent. ;  at  4  horse-power,  84  cubic 
feet,  or  46  per  cent.,  and  at  2  horse-power,  60  cubic  feet,  or  33  per 
cent.  The  waste  in  fuel  gas  under  low  speed  and  low  power  con- 
ditions may  thus  be  readily  understood — one-sixth  of  the  stated 
horse-power  from  one-third  of  the  full  gas  supply.  It  may  thus 
be  understood  why  that  the  speed  of  the  engine,  usually  ex- 
pressed as  "revolutions  per  minute"  of  the  fly-wheel,  is  an  im- 
portant item  in  all  formulae  for  calculating  the  horse-power.  The 
gas  engines  built  for  automobile  use  are  invariably  of  high  speed- 
capacity,  and  also  represent  the  highest  point  of  economy. 

Because  of  the  fact  that  a  reduction  of  the  charge  involves  a 
nearly  corresponding  loss  of  power  output  in  a  gas  engine,  it  is 
usually  believed  that  the  speed  of  the  carriage  can  be  varied 
only  by  the  change-speed  gear.  On  this  point,  however,  Mr.  C. 
E.  Duryea  says : 

"In  order  to  vary  the  speed  of  a  carriage  on  a  given  road,  it 
is  necessary  to  vary  the  fuel  supply,  because  if  the  lower  gear  is 
used,  the  engine,  having  less  work,  will  race  and  the  governor 
must  then  act,  which  is  a  method  of  varying  the  fuel  supply. 
The  speed-changing  gear  is  provided  in  connection  with  gaso- 
line engines,  because  such  engines  are  not  provided  with  vari- 
able cut-offs  and  are,  therefore,  not  considered  economical  with 
various  sized  charges.  On  this  account  a  motor  of  average 
size  is  used,  and  its  deficiencies  made  up  for  by  change  of  gear- 
ing. The  Duryea  practice  is  to  provide  a  large  motor,  just  as  is 
done  with  a  steam  engine,  and  to  throttle  it  over  a  wide  range 
regardless  of  the  loss  of  economy.  As  a  matter  of  fact,  this  loss 
is  more  seeming  than  real,  for,  with  the  speed-changing  mechan- 
ism, a  constant  mechanical  loss  is  present  which  balances  largely, 
if  it  does  not  exceed,  the  efficient  loss  of  the  motor  by  throttling. 
We  are,  therefore,  able  on  good  roads  to  drive  our  carriages  at 
from  three  to  thirty  miles  per  hour  by  varying  the  speed  of  the 
motor  by  a  throttle,  and  we  use  the  gearing  only  for  hills  that 
are  beyond  the  capacity  of  our  motor  as  ordinarily  geared." 

Heat  Economy:  Spherical  Clearance — A  number  of  gas 
engines  achieve  an  economy  in  the  use  of  heat  and  power  units 
by  having  the  piston  and  the  combustion  chamber  of  concave 


CYLINDER    COOLING   DEVICES. 


195 


profile,  so  as  to  form  a  spherical,  spheroidal  or  elliptical  clearance 
at  the  end  of  the  in-stroke.  That  is  to  say,  the  rear  end  of  the 
cylinder  is  dome-shaped  and  unjacketed,  and  the  opposing  end  of 
the  trunk  piston  is  correspondingly  hollowed  or  concaved.  The 
spheroidal  clearance,  formed  when  they  are  in  contact  or  prox- 
imity, is,  of  course,  deformed  as  the  piston  makes  its  out-stroke, 
but  the  end  of  economizing  a  considerable  percentage  of  heat 
units  is  conserved  by  thus  providing  a  large  uncooled  surface  at 
either  end  of  the  combustion  chamber  during  the  entire  cycle 
Indeed,  while  this  arrangement  permits  of  a  clearance,  at  the  end 
of  the  in-stroke,  of  the  smallest  possible  area  on  the  cylinder 


FIG.  145.— The 
or  jacket  wat 
quantity  of 


Instead  of  wing  flanges, 
r  by  injection  of  a  small 
ater  comes  through  the 


lower  tube  to  the  left  of  the  cylinder  head,  passing  through  the  three-way  cock,  A, 
and  the  ball  valve,  B.  The  lift  of  the  ball  valve  is  determined  by  the  adjusting 
screw,  C.  When  water  is  not  required,  the  three-way  cock  is  turned  so  as  to  return 
it  to  the  tank  through  the  upper  left-hand  tube.  The  theory  is  that  superfluous  heat 
will  be  absorbed  in  vaporizing  the  injected  water. 

walls,  it  provides  a  total  increase  in  clearance  volume  on  a  stated 
wall  surface  between  20  and  40  per  cent,  in  engines  of  ordinary 
design.  Hiscox  estimates  that,  while  the  wall  surface  of  a  cylin- 
drical clearance  space  of  one-half  its  unit  diameter  in  length  con- 
tains 3.1416  square  units  and  0.3927  cubic  unit,  the  same  surface 
in  square  unit  measure,  with  a  spherical  combustion  chamber 
has  a  volume  of  0.5236  cubic  unit,  representing  a  gain  in  volume 
of  33  i-3  Per  cent-  (5236—3927=1309x3=3927).  Such  superior 
volume,  on  equal  wall  surface,  being  fully  available  at  the 
moment  of  explosion,  when  the  greatest  possible  degree  of  heat 


19C) 


SELF-PROPELLED   VEHICLES. 


and  pressure  is  desirable  to  promote  expansion,  must  vastly  in- 
crease the  effective  power  of  the  engine.  Furthermore,  although 
this  arrangement  is  perfectly  satisfactory  in  checking  the  absorp- 
tion of  heat  units  until  the  full  force  of  the  explosion  has  been 
realized,  it  is  ineffective  for  producing  a  hot  surface,  firing  tem- 
perature, such  as  is  seen  in  the  Hornsby-Akroyd  engines,  from 
the  fact  that  the  concave  surfaces  of  cylinder  end  and  piston  head 
are  open  to  a  large  heat-absorbing  space,  and  hence  quickly  fall 
in  temperature. 

Heat  Economy  :  Temperature  of  Water. — Another  consider- 
eration  of  importance  in  calculating  for  heat  economy  in  a  gas 
engine  is  that  the  temperature  of  the  jacket  water  should  be 
maintained  at  a  point  favorable  to  moderate  absorption  of  heat 


FIG.  146.— Details  of  Two  Descriptions  of  Water  Cooling  Radiators.  In  the  first,  the  pipe 
is  surrounded  by  metal  fins,  let  on  as  indicated;  in  the  second,  it  is  surrounded  with 
coils  of  helical  wire. 

units.  It  is  an  error  of  somewhat  common  occurrence  to  sup- 
pose that  the  conditions  of  cycular  operation  demand  that  this 
temperature  be  as  low  as  possible ;  the  popular  notion  being  that 
the  cylinder  requires  some  kind  of  freezing  process  in  order  to  be 
properly  "cooled."  As  we  have  already  stated  the  real  object  of 
the  cylinder  cooling  system,  it  is  necessary  only  to  add  that  the 
requirement  is  that  the  temperature  should  be  kept  somewhat 
below  a  definite  high  point,  and  that,  as  can  be  readily  under- 
stood at  this  stage,  the  efficiency  of  the  engine  is  decreased  very 
nearly  in  proportion  to  the  thermometric  fall  below  that  point. 
Thus  if  we  play  a  jet  of  water  from  an  ordinary  garden  hose  upon 
a  gas  engine  in  operation,  we  will  very  quickly  discover  that  its 
motion  is  effectually  checked ;  whereas,  if  we  supply  the  jacket 
system  with  water  of  slightly  below  100°,  Centigrade,  we  will 


CYLINDER    COOLING   DEVICES. 


197 


discover  that  the  efficient  power  is  increased  in  ratio  with  the 
rise  in  temperature.  Thus,  as  is  being  advocated  by  some  of  the 
foremost  authorities  on  the  subject,  the  best  practice  is  to  supply 
water  to  the  jacket  at  a  temperature  of  a  few  degrees  below  the 
boiling  point,  permitting  it  to  be  returned  to  the  reservoir  at  a 
temperature  slightly  above.  Some  hold  that  even  higher  tem- 
peratures are  practicable. 

A  well-known  manufacturer  of  gasoline  carriage  motors 
writes  as  follows :  "A  motor  is  hotter  when  the  water  is  boiling 
rapidly  than  when  it  is  boiling  slowly,  and  the  fact  that  more 


FIG.  147«-Fin  Cooled  Radiating  Tubes  used  on  the  "Dyke"  Carriages,  with  parts  and 

connections  indicated. 

heat  units  are  being  absorbed  by  the  water  proves  that  the  en- 
gine is  doing  harder  work  and  not  that  it  is  cooler  than  before. 
The  writer  favors  boiling  water  as  the  proper  temperature  and 
a  gravity  circulation  as  the  proper  circulating  method,  because 
this  method  most  nearly  insures  a  fixed  temperature  for  the 
motor  to  work  under.  If  kept  below  the  boiling  point  the  tem- 
perature of  the  motor  will  vary  as  the  work  varies.  If  air-cooled 
it  will  vary  with  the  wind  or  the  speed  of  the  vehicle.  If  circu- 
lated by  pump  the  temperature  will  vary  as  the  speed  of  the 
pump  varies,  but  with  the  boiling  water  system  it  remains  rea- 
sonably constant  and  permits  the  finest  adjustment  of  the  mix- 
ture and  the  best  results  from  the  sparking."  Other  authorities 
seem  to  disagree  with  his  position. 


Heat  Economy :  Rate  of   Water  Circulation  — In  the  excel- 
lent and  suggestive  treatise  on  "Gas  and  Oil  Engines/'  given  in 


198 


SELF-PROPELLED    VEHICLES. 


"Power  Quarterly,"  for  October,  1900,  occurs  the  following  sig- 
nificant passage : 

"The  more  rapidly  the  water  passes  through  the  jacket,  the 
lower  will  be  the  temperature  of  the  issuing  jacket  water,  but  the 
heat  units  will  be  greater,  within  the  usual  limits  of  practice.  For 
example,  suppose  the  jacket  water  passes  through  at  the  rate  of 
16  pounds  a  minute  and  rises  from  60°  F.  to  140°  F.  in  passing 
through.  To  raise  16  pounds  of  water  80  degrees  requires  1,280 
B.  T.  U.  (British  thermal  units),  and  as  the  difference  between  the 


Fio.  148.  — "  Crest "  Double-Opposed  Cylinder  Gasoline  Vehicle  Engine,  showing  radiating 
ribs  for  co9ling  cylinders.  The  cylinders  of  this  motor  are  in  line,  not  off-set,  as  in 
some  makes,  the  two  cranks  working  on  one  crank  pin.  Owing  to  the  method  of  join- 
ing the  crank  case  on  its  diameter,  all  the  working  parts  may  be  readily  reached  by 
unscrewing  four  bolts.  Among  the  special  features  of  this  motor  are  the  relief  valve, 
which  opens,  hence  interrupting  operation  as  the  wagon  coasts  down  hill,  and  the 
automatic  cut  out  for  the  battery  circuit  which  operates  when  the  engine  is  at 
a  standstill. 

average  temperature  within  the  cylinder  (usually  about  1,000° 
F.)  and  that  of  the  jacket  water  (in  this  case  100°)  is  900  degrees, 
there  are  1,422  heat  units  per  minute  transmitted  through  the 
walls  of  the  cylinder  per  degree  of  difference  between  inner  and 
outer  average  temperatures. 

"Now  reduce  the  rate  of  flow  of  the  jacket  water  to  9.57 
pounds,  and,  assuming  that  the  average  temperature  in  the  cylin- 
der remains  constant,  the  water  will  issue  at  a  temperature  of  190° 
F.  This  means  a  rise  of  130  degrees,  and  to  heat  9.57  pounds  of 
water  per  minute  130  degrees,  will  require  9.57x130  =  1,244 
heat  units  per  minute,  which  is  36  less  than  before.  A  saving  of 
36  heat  units  per  minute  means 


CYLINDER    COOLING   DEVICES. 

"As  a  matter  of  fact  the  flow  of  water  would  need  to  be  less 
than  9J  pounds  a  minute  in  order  to  raise  the  temperature  to  190° 
F.,  because  as  the  jacket  water  increases  in  temperature,  the 
average  temperature  in  the  cylinder  increases,  making  the  differ- 
ence between  the  two  less  than  if  the  internal  temperature 
remained  constant.  This  decreases  the  transmission  of  heat 
units  to  the  water.  The  effect  of  varying  the  flow  of  jacket  water 
cannot  be  computed  accurately,  because  the  internal  temperature 
cannot  be  computed,  and  the  exact  heat  conductivity  of  the  cylin- 
der walls  is  unknown.  But,  as  the  foregoing  rough  example 
clearly  shows,  the  temperature  of  the  issuing  jacket  water  should 
be  kept  as  high  as  practicable  by  adjusting  the  rate  of  flow. 

"The  limit  to  the  allowable  increase  in  jacket  water  tem- 
perature is  set  by  the  cylinder  oil.  The  cylinder  walls  must  not 
be  allowed  to  become  so  hot  as  to  decompose  the  oil,  for  the  very 
obvious  reason  that  decomposed  oil  does  not  lubricate.  When 
the  construction  of  an  engine  is  such  that  the  piston  cannot  be 
inspected  there  is  no  reliable  way  of  determining  the  conditions 
of  lubrication  at  high  temperatures  without  endangering  the 
cylinder  wall  and  piston  surface.  But,  as  a  rule,  the  jacket  water 
can  be  run  up  to  200°  F.  without  risk  of  decomposing  the  cylin- 
der oil,  if  a  first-class  oil  is  used." 

Such  principles  as  have  been  mentioned  thus  far  are  competent 
in  evidence  for  the  statement  that  the  operative  conditions  of  the 
gas  engine  strike  a  balance  between  very  definite  extremes  in  sev- 
eral particulars,  which,  if  not  carefully  -noted,  quickly  reduce  both 
the  motion  and  the  effective  power-output.  We  have  scarcely 
stated  that  the  cylinder  must  be  regularly  cooled,  when  we  are 
obliged  to  modify  the  assertion  by  saying  that  it  must  not  be  too 
cool,  nor  yet  too  hot,  lest  the  very  difficulties  we  aim  to  avoid  occur 
with  even  greater  danger.  The  same  dilemma  is  met  in  the  at- 
tempt to  provide  against  the  over-absorption  of  heat  units  by 
regulating  the  circulation  rate  of  the  jacket  water :  If  the  rules 
for  ensuring  economy  are  carried  too  far  the  good  effects  of  the 
cooling  are  neutralized.  Water  in  a  paper  bag  may  be  boiled  over 
a  gas  flame,  because  it  absorbs  heat  faster  than  does  the  paper. 
In  the  same  way,  by  the  use  of  a  water  cooling  system,  a  tem- 
perature very  near  to  the  melting  point  of  steel  (2560°  F.,  3021° 
absolute)  may  be  reached  at  the  explosion  moment  of  the  fuel 
gas  in  the  cylinder,  without  destroying  the  engine  or  decom- 


200  SELF-PROPELLED   VEHICLES. 

posing  the  lubricating  oil,  which  carbonizes  usually  at  a  tempera- 
ture of  about  i, 000°,  Fahrenheit,  more  or  less. 

Jacket  Water  Circulation — With  the  gas  engines  used  for 
stationary  power  purposes,  the  jacket  water  may  be  drawn  from 
and  returned  to  a  special  tank  or  reservoir,  thus  ensuring  suffi- 
cient circulation  to  regulate  the  temperature  of  the  water  fed  to 
the  jacket,  but  with  many  vehicle  motors  is  used  a  supplementary 
radiating  cooler,  through  which  the  ejected  water  passes  on  its 
way  back  to  the  tank.  The  most  approved  form  of  such  a  cooler, 
as  used  at  present,  consists  in  a  coil  or  train  of  copper  tubes,  on 
which  are  sprung  rows  of  fins,  or  flanges,  of  tin  or  aluminum. 
Another  form  has  the  same  train  of  tubes  spirally  corrugated  and 
wrapped  about  with  lengths  of  wire  rolled  into  very  nearly  the 
shape  of  a  spiral  spring.  The  spring,  or  flanges,  just  mentioned 
consist  of  a  number  of  metal  discs,  in  the  centre  of  each  of  which 
an  X-shaped  cut  is  made.  The  points  thus  formed,  being  bent 
back,  leave  an  orifice  for  introducing  the  tube,  and  when  the  discs 
are  in  place  serve  to  keep  them  at  proper  distance.  The  fins  afford 
a  large  heat-radiating  surface  for  the  water  tubes,  which  is  further 
increased  by  so  lengthening  and  coiling  the  pipes  as  to  expose  the 
greatest  possible  surface  to  the  air,  under  draught.  The  standard 
Daimler  cooling  device  is  a  tank  at  the  front  of  the  bonnet  pierced 
by  a  large  number  of  tubes,  like  a  fire  tube  boiler. 

Circulating  Pumps — The  circulating  pump  is  most  commonly 
used  in  the  belief  that  it  affords  a  ready  means  for  regulating  the 
rate  and  temperature  of  the  jacket  water  supply,  which  could  not 
always  be  the  case  with  a  mere  gravity  system.  Such,  however, 
is  not  precisely  the  case ;  since  such  pumps,  being  generally  driven 
direct  from  the  motor,  operate  at  a  speed  varying  with  the  motor 
speed.  Thus,  on  starting  the  motor,  it  begins  pumping  cold  water 
into  the  jacket,  although  no  occasion  exists.  It  pumps  slowly 
at  slow  speeds,  although  the  motor  may  be  taking  large  charges 
and  heating  itself  rapidly,  as  when  ascending  steep  hills.  It  also 
pumps  rapidly  at  high  speeds,  although  the  wind  pressure  and 
cooling  effect  may  be  very  great,  as  on  smooth  roads.  Could 
such  circulation  pumps  be  always  used  in  connection  with  a  ther- 
mostat, in  order  to  operate  to  the  even  regulation  of  the  motor 
temperature,  the  results  would  be  much  more  favorable. 


CYLINDER   COOLING  DEVICES. 


201 


Solutions  to  Prevent  Freezing — In  order  to  prevent  freez- 
ing, the  jacket  water,  when  the  engine  is  not  in  operation  in  cold 
weather,  solutions  are  used,  notably  of  glycerine  and  of  calcium 
chloride  (Ca  Cl2).  The  proportions  for  the  former  solution  are 
equal  parts  of  water  and  glycerine,  by  weight ;  for  the  latter,  ap- 
proximately, one-half  gallon  of  water  to  eight  pounds  Ca  Cl',  or 
a  saturated  solution  at  60°,  Fahrenheit.  This  solution  (Ca  Cl2  -f- 
6  H2  O)  is  then  mixed  with  equal  parts  of  water,  gallon  for  gal- 
lon. Many  persons  complain  that  Ca  Cl"'  corrodes  the  metal  parts, 
but  this  wrarning  need  do  no  more  than  urge  the  automobilist  to 
use  only  the  chemicallv  pure  salt,  carefully  avoiding  the  "chloride 
of  lime"  (CaOCl2). 


FIG.  149.— Detail  Cylinder  Head  of  the  Simms  Cycle  Motor,  showing  fan 
wheel,  cooling  ribs,  and  peculiar  arrangement  for  opening  the  exhaust. 
Similar  fan  wheels  are  used  on  several  types  of  light  vehicle  motor. 

Air  Cooling  for  Cylinders. — While,  as  a  general  proposition, 
it  may  be  said  that  the  cooling  of  a  gas-engine  cylinder  is  best 
accomplished  by  water-circulation,  a  number  of  recent  carriages 
both  light  and  heavy  have  successfully  used  air-cooling  devices. 
To  within  a  very  few  years  it  has  bee,n  held  that  air  cooling  is 
impracticable  for  vehicle  motors,  and,  on  the  basis  of  trials  made 
by  French  builders,  the  statement  has  always  been  made  that, 
while  an  air-cooled  cylinder  will  work  very  well  on  a  light  high 
speed  vehicle  or  cycle,  it  is  impossible  for  automobiles  of  large 
power,  particularly  in  climbing  hills  and  in  hot  weather.  Daim- 
ler's early  motors  were  air  cooled  by  means  of  a  rotary  fan  on  the 
crankshaft  that  created  a  forced  draught  through  an  air  jacket 
surrounding  the  cylinder,  as  is  shown  in  a  subsequent  cut.  Later 
on,  automobile  builders,  such  as  Mors,  Decauville,  Darracq,  and 


202 


SELF-PROPELLED   VEHICLES. 


also  Panhard-Levassor,  used  motors  on  heavy  carriages  with 
the  cylinders  cooled  by  peripheral  fins  or  flanges.  The  principal 
trouble  with  these  cylinders  was  that  under  heavy  load  the  gen- 
erating of  heat  was  so  rapid  as  to  clog  the  piston,  ignite  the 
lubricating  oil,  or  to  produce  premature  explosion  of  the  charge. 
Largely  for  this  reason,  the  water-cooling  system  become  univer- 
sal, except  for  very  light  vehicles  and  cycles  intended  to  be  driven 
at  high  speeds.  In  order  to  assist  the  work  of  cooling  the  cylin- 
der, several  builders  early  adopted  the  plan  of  using  rotary  fans 
to  create  a  forced  draught  against  the  fins  cast  on  the  cylinder's 
walls.  Such  a  device  greatly  increased  the  cooling  properties  of 


FIG.    150.rThe  "Knox"  Pin-Cooled  Cylinder.     In  this  engine,  pins  are  used  for 
radiating  instead  of  the  usual  flanges  or  ribs  as  on  other  air-cuoled  cylinders. 

the  motor,  even  when  the  vehicle  was  moving  at  low  speed.  This 
was  particularly  true  with  the  Simms  fan-cooled  cylinder,  on  the 
walls  of  which  were  cast  very  deep  longitudinal  flanges.  An 
English  builder,  Turell,  constructed  a  three-wheeled  carriage 
propelled  by  a  motor  with  ribs  of  this  description.  It  was  found 
however  that,  with  a  motor  of  2.  horse-power,  and  over,  the  draught 
created  at  high  speed  was  not  sufficient  for  cooling  and  that  the 
cylinder  would  quickly  become  overheated,  with  the  result  the 
exhaust  walls  would  be  loosened  and  the  head  frequently  red  hot. 
It  seems  to  have  been  reserved  for  American  inventors  to  design 


CYLINDER    COOLING   DEVICES. 


203 


successfully  air-cooling  systems.  One  of  the  most  noteworthy 
of  this  is  the  Knox  pin-cooled  cylinder,  in  which  a  large  number 
of  brass  pins  are  screwed  into  suitable  holes  on  the  outside  of  the 
cylinder's  wall.  According  to  claims  this  device  increases  the 
cooling  surface  nearly  100  per  cent.,  and  is  exceedingly  efficient 
in  utilizing  the  heat  absorbing  properties  of  air  under  draft.  In 
connection  with  the  use  of  corrugated  pins  on  the  outside  surface 
of  the  cylinder,  a  rotary  fan  is  used,  and  this,  being  driven  direct 
from  the  main  shaft  by  a  worm  gear,  always  rotates  with  the 


FIG.     151.— Knox     Single-cylinder     Four-wheeled     Car,     showing     pin-cooled 
cylinder  and  great  length  of  motor. 

speed  of  the  engine,  thus  providing  a  sufficient  draught  for  cooling 
purposes  at  all  speeds.  The  problem  has  been  differently  solved 
by  other  American  inventors.  Thus  the  builders  of  the  Crest 
carriage  use  a  cylinder  with  deep  longitudinal  flanges,  which 
according  to  claims  and  reported  tests  is  very  efficient  in  spite  of 
tfie  fact  that  the  motor  is  set  vertically  in  the  carriage.  Briefly 
described,  the  flanges  are  so  arranged  as  to  be  deepest  over  the 
combustion  spaces,  thus  giving  the  cylinder  an  approximate  pear 
shape.  The  success  of  the  air  cooling  is  due  to  the  extremely 
large  radiating  surface,  due  to  the  use  of  very  wide  vertical 


204 


SELF-PROPELLED   VEHICLES. 


radiating  vanes,  to  the  free  passage  of  air  directly  behind  the 
valve  chamber — this  space  being  usually  filled  with  solid  metal — 
and  to  the  slight  tapering  of  the  upper  end  of  the  piston.  The 
motor  is  of  the  conventional  vertical  type,  excepting  that  the 
inlet  and  exhaust  valves  are  larger  in  proportion  to  bore  than  is 
usually  used.  According  to  claims,  apparently  verified  by  inde- 
pendent test,  it  can  safely  run  at  a  speed  of  between  1,900  and 
2,000  revolutions  per  minute. 


FIG.    152. — Franklin     Four-cylinder    24-horse-power     Engine, 
number  of  flanges  for  cooling  the  cylinders. 


showing    great 


The  Franklin  system  of  air  cooling  is  different  from  either  of 
the  foregoing  although  equally  efficient  in  operation.  The  plan 
is  to  use  a  four-cylinder  motor  of  small  bore  and  short 
stroke,  3^  x  3^2  being  the  dimensions  for  the  cylinders  of"  a 
12-horse-power  engine.  Combined  with  this  is  slow  speed;  two 
together  enabling  superfluous  heat  to  be  rapidly  absorbed  as  the 
car  travels.  The  flanges  of  the  cylinder  are  very  numerous,  al- 
though not  of  great  depth. 


CYLINDER   COOLING  DEVICES.  205 

The  most  recent  device  for  air-cooling  of  cylinders  is  that  used 
on  the  Regas  engine,  upon  the  outside  walls  of  which  is  placed  a 
sheet  stetl  jacket  carrying  172  copper  tubes  of  l/2  inch  diameter 
and  il/2  inches  long  Each  of  them  has  longitudinal  slots  near  its 
base.  As  heat  is  generated  in  the  operation,  of  the  motor,  a 
circulation  of  air  is  set  up,  the  hot  air  being  given  out  at  the  ends 
of  the  tubes,  on  the  principle  of  the  Bun'sen  burner.  In  this 
manner,  there  is  a  constant  supply  of  cool  air  for  absorbing  the 
heat  of  the  cylinder  and  the  circulation  is  maintained  apart  from 


FIG.  153.— Cylinder  of  the  Regas  Motor,  showing  Bunsen  tubes  let  into  steel 
jacket. 


the  use  of  a  fan  or  other  mechanical  contrivance.  According  to 
claims,  a  4^2x5  double  inclined  cylinder  motor,  developing  12 
horse-power  at  1,200  revolutions,  can  be  perfectly  cooled  by  the 
use  of  172  of  such  Bunsen  tubes  in  each  cylinder. 

A  cylinder  with  such  a  Bunsen  tube  cooler  can  be  perfectly 
operated  on  a  stationary  engine  running  at  1,000  revolutions  per 
minute. 


CHAPTER    SEVENTEEN. 

ON   FUEL  MIXTURES   AND   THE   CONDITIONS  RESULTING  FROM 
COMBUSTION   OF  THE   CHARGE. 

Causes  of  Imperfect  Combustion. — In  addition  to  the  gen- 
eral conditions  of  gas  engine  efficiency  thus  far  given,  it  is  im- 
portant to  consider  the  cause  and  consequences  of  imperfect 
combustion,  which,  as  may  be  readily  understood,  is  a  fertile 
source  of  irregular  action  and  loss  of  power.  In  the  first  place, 
it  is  important  to  consider  the  matter  of  proper  proportions  of 
air  and  gas  in  the  fuel  mixture,  since  too  much  or  too  little  of 
either  element  results  in  weak  explosion.  Practically,  this  is  a 
question  of  proper  carburization,  and  may  be  determined  by  ex- 
perience quite  as  efficiently  as  by  calculations.  In  the  second 
place,  sufficient  compression  of  the  fuel  gas  should  be  provided 
for,  in  order  that,  despite  the  presence  of  the  exhausted  products 
of  previous  combustion,  there  may  be  an  adequate  mixture  of 
the  charge,  giving  a  fair  degree  of  uniformity  throughout.  The 
result  of  an  uniform  mixture  is  to  provide  one  condition  of  rapid 
firing,  since  the  gradual  and  partial  combustion,  so  frequently 
a  source  of  annoyance  and  lost  efficiency  in  gas  engines,  comes 
directly  from  imperfect  mixture  under  compression.  This 
brings  us  to  the  third  point — what  method  of  firing  is  the  most 
efficient  in  securing  the  quickest  possible  combustion?  The 
first  point  involves  several  important  considerations,  which  we 
will  now  proceed  to  touch  briefly ;  the  second  is  largely  a  matter 
of  structural  proportions,  after  the  question  of  proper  mixture 
has  been  determined,  as  is  indicated  by  much  already  said ;  the 
third  will  be  fully  discussed  under  the  head  of  firing  devices. 

The  Theory  of  Fuel  flixtuf  es.  —The  object  of  mixing  at- 
mospheric air  with  the  fuel  gas  is  to  obtain  a  sufficient  amount  of 
oxygen  to  enable  combustion  to  take  place.  All  oils  and  spirits 
may  be  ignited  and  burned  at  the  proper  temperature,  differing 
for  each  particular  substance,  if  that  temperature  be  produced 
where  air  can  circulate  freely.  At  certain  definite  temperatures 
such  liquids  give  off  inflammable  vapors,  and  at  a  somewhat 

306 


EXPLODING    THE  FUEL    CHARGE.  207 

higher  point  may  be  ignited  and  burned  themselves.  The  first 
point  is  called  the  flash  point;  the  second,  the  fire  point.  However, 
when  shut  off  from  air  supply,  neither  the  vapor,  so  formed,  nor 
the  liquid  itself  may  be  ignited.  This  is  the  reason  why  that  oil 
vapor  may  be  fed  into  the  superheated  combustion  chamber  of 
the  Hornsby-Akroyd  engine,  as  already  described,  and  fail  to 
explode  until,  by  the  completion  of  the  compression  stroke,  a 
sufficient  quantity  of  atmospheric  air  has  been  mixed  with  it. 

In  order  to  illustrate,  the  following  list  of  several  familiar  hy- 
drocarbons, together  with  their  flash  and  fire  points,  is  quoted 
from  a  well-known  authority : 

Flash  Point.     Fire  Point. 

Commercial   brandy    69  92 

whiskey    72  96 

gin    72  101 

Kerosene   (average   quality) 73  104 

Petroleum  (high  test) 1 10-120  140-160 

Proportions  of  Fuel  flixtures. — In  the  free  air  the  only 
point  to  be  considered  is  the  required  temperature  for  flashing 
or  firing,  since  atmospheric  circulation  will  always  supply  the 
full  amount  of  oxygen  for  combustion.  In  a  gas  engine  cylin- 
der, closed  from  the  outer  air,  it  is  necessary  to  know  how  much 
air  must  be  admitted.  The  most  efficient  proportions  of  air  and 
gas,  mixed  to  give  a  perfect  combustion  in  a  closed  cylinder  may 
be  considered  a  matter  in  many  respects  relative  to  the  kind  of 
gas  employed — some  gases  require  more,  some  less,  for  the  best 
effects  from  combustion.  In  general,  however,  the  data  on  coal 
gas  may  be  taken  as  typical  for  most  fuels  available  in  ordinary 
gas-engine  service.  With  this  fuel  the  figures  for  efficiency 
range  between  6  to  i  and  n  to  i  for  air  and  gas,  respectively. 
That  is-to  say,  with  a  mixture  of  about  5  to  i  or  of  about  12  to  i, 
for  example,  the  effective  pressure  due  to  combustion — if  com- 
bustion is  possible  at  all — shows  a  marked  falling  off,  which  con- 
tinues thereafter  as  the  proportion  of  air  in  the  mixture  is  di- 
minished or  increased.  Between  the  efficient  extremes,  how- 
ever, it  has  been  found  that,  although  the  actual  indicated  ex- 
plosion pressure  decreases  in  ratio  with  the  increased  percentage 
of  air  in  the  mixture,  the  efficiency  steadily  increases  until  the 
point  of  ii  to  i  is  approximated.  This  fact  is  explained  by  as- 


208 


SELF-PROPELLED   VEHICLES. 


FIG.  154.  —Gas  Engine  Indicator  Cards.  The  first  diagram  is  an  average  good  card,  show- 
ing, however,  some  slight  fluctuations  in  the  lines.  The  explosion  line  is  from  C  to 
A;  the  expansion,  from  A  to  B;  the  exhaust  at  B.  The  suction  stroke  generally 
approximates  the  atmospheric  line,  from  which  the  curve  of  compression  rises  to  C. 

The  second  diagram  is  from  an  engine  running  under  half  load;  the  third  from  one  at  full 
load.  Both  exhibit  the  variations  in  the  expansion  curve,  usually  attributed  to  con- 
secutive explosions.  The  second  and  third  cards  are  composites  of  three  successive 
strokes  each. 


EXPLODING  THE  FUEL   CHARGE.  209 

suming  that,  in  increasing  the  proportion  of  air  in  the  mixture, 
the  temperature  per  unit  of  gas  is  raised,  although  the  tempera- 
ture per  unit  of  the  mixture  of  gas  and  air  is  lowered.  Since, 
therefore,  the  gas  itself  is  the  sole  agent  of  efficiency — the  con- 
dition necessary  to  explosion  being  all  that  is  furnished  by  the 
admixture  of  air — the  increase  in  the  proportion  of  air  in  the 
charge,  up  to  the  specified  limit,  increases  the  total  efficiency, 
even  though  lowering  the  pressure  of  the  explosion. 

Some  Results  of  Imperfect  Compression. — On  account  of 
another  consideration,  the  proper  proportion  of  air  and  gas  for 
a  given  case  is  important,  and,  when  combined  with  an  ade- 
quately adjusted  compression,  is  a  factor  in  promoting  efficiency. 
This  refers  to  the  fact  that,  as  shown  by  numerous  indicator  dia- 
grams, the  firing  of  the  whole  mass  of  gas,  contained  in  cylin- 
der, is  not  always  an  instantaneous  process — some  diagrams 
showing  several  consecutive  explosions,  of  decreasing  effect  to  be 
sure,  which  tend  to  make  the  action  of  the  engine  fluctuating  and 
uncertain.  This  effect  has  been  ascribed  to  a  "defective  mix- 
ture," but  such  could  not  be  the  sole  cause  of  all  the  phenomena, 
since  alone,  it  would  rather  occasion  an  explosion  of  insufficient 
pressure,  if  any  explosion  at  all.  The  truth  is  that  the  mixture, 
in  such  cases,  is  defective  from  the  fact  that  it  does  not  contain 
sufficient  oxygen  to  the  total  bulk  to  produce  perfect  ignition, 
in  view  of  the  presence  of  burned  out  gases  in  the  clearance.  As 
described  by  some  writers  on  the  subject,  these  residua  of  pre- 
vious combustions  develop  the  tendency  to  stratify  the  mixture, 
and,  unless  the  air  is  in  proper  preponderence  to  the  percentage, 
of  pure  fuel  gas,  or,  unless  the  compression  ratio  is  adjusted  to 
produce  adequate  blending  of  the  inflammable  elements,  the  re- 
sult will  be  several  explosions,  as  the  successive  layers  of  gas, 
separated  by  unburnable  products,  become  ignited.  Among  other 
elements  that  combine  to  promote  the  conditions  just  specified 
are  certain  chemical  changes,  giving  rise  to  gases  of  high  fire 
temperatures,  or  causing  shrinkage  in  the  proportion  of  good 
fuel  mixture  in  the  cylinder.  Defective  or  inferior  firing  devices 
are  also  liable  to  produce  slow  and  irregular  combustion. 

As  many  of  the  conditions  of  gas  engine  operation  seem  to  be 
somewhat  uncertain,  in  the  minds  of  even  prominent  authorities, 
it  is  only  fair  that  we  quote  several  opinions  contrary  to  those  al- 


210 


SELF-PROPELLED    VEHICLES. 


ready  stated.  A  well-known  designer  and  manufacturer  of 
vehicle  motors,  in  a  letter  to  the  author,  denies  the  theory  of 
"stratification"  of  the  charge  with  the  residua  of  previous  com- 
bustions, asserting  that  the  indicator  diagram  phenomena, 
usually  attributed  to  several  successive  explosions,  are  due 
rather  "to  irregularities  of  the  indicator  or  to  vibrations  of  the 
gas  in  the  indicator  piping,  and  not  to  variations  in  the  rate  of 
combustion."  He  also  deprecates  the  importance  given  by 
some  writers  to  the  efficiency  of  a  high  compression  in  produc- 
ing a  better  blending  of  the  fuel  mixture,  attributing  the  good 
results,  apparently  thus  obtained,  to  the  time  occupied  in  mak- 
ing the  compression,  which  also  serves  to  perfect  the  mixture, 
and  also  to  the  fact  that  compression  produces  heat,  thus  also 
promoting  readiness  of  ignition. 


FIG.  155.— The  Benz  Exhaust  Muffler.  The  arrows  indicate  the  course  of  the  expanding 
exhaust  products.  Entering  at  the  left,  they  pass  through  the  perforations  in  the 
tube;  thence  through  the  smaller  tube  in  the  larger  chamber;  again  through  the  per- 
forations in  the  right-hand  section  of  the  tube,  and  to  atmosphere.  The  breaking-up 
of  the  gas  in  expansion  silences  the  noise  of  its  exhaust  to  atmosphere. 

Defective    Combustion:    Advantages    of    Scavenging. — In 

addition  to  the  irregularities  of  action,  just  enumerated,  the  pres- 
ence of  burned  out  gases  in  the  clearance  operates  effectually 
to  reduce  both  the  pressure  and  temperature  of  combustion  by 
several  per  cent.  This  fact  is  demonstrated  by  comparing  the 
figures  for  explosion  pressures  and  temperatures  of  scavenging 
and  non-scavenging  gas  engines  of  the  same  proportions.  For 
although,  as  we  have  already  seen,  the  figures  for  compression 
pressure  and  temperature  are  higher  for  non-scavenging,  or  or- 
dinary, gas  engines  than  for  the  other  variety,  due,  as  has  been 
asserted,  to  the  recompression  of  burned  products  in  the  one  en- 
gine, or  else  to  the  use  of  cooling  air  currents  to  expel  these  in 
the  other,  the  case  is  directly  reversed  at  the  moment  of  ex- 


EXPLODING  THE  FUEL   CHARGE.    '  21 1 

plosion.  From  this  fact,  as  may  be  readily  understood,  a  scav- 
enging engine  should  be  the  more  effective,  as  securing  the  bet- 
ter ignition  of  the  charge  and  as  permitting  the  loss  of  less  heat 
in  proportion  to  the  total  of  units  generated.  The  principle  has 
been  adopted  successfully  with  several  well-known  types  of  sta- 
tionary gas  engine,  although,  so  far  as  the  writer  can  ascertain, 
few,  if  any,  attempts  have  been  made  to  adapt  it  to  use  in  motor 
vehicles. 

Its  inefficiency  in  this  connection  would  arise  from  several 
conditions,  prominent  among  which  would  be  the  added  compli- 
cation necessary  to  the  end  of  eliminating  the  burned  gases  under 
high  speed  conditions  and  the  uncertainty  involved,  with  the 
constantly  recurring  danger  of  thus  lowering,  rather  than  raising, 
the  value  of  the  charge  by  irregular  variation  of  the  mixture. 
Also  the  rate  of  jacket  water  consumption  would  always  be 
greater  owing  to  higher  temperatures.  The  force  of  these  re- 
marks may  be  understood  when  we  consider  that  the  most  usual 
and  practical  method  of  scavenging  a  gas  engine  cylinder  is  to 
drive  out  the  burned  residua  by  admitting  a  current  of  fresh  air 
into  the  clearance.  The  method  of  extending  the  sweep  of  the 
piston  clear  to  the  rear  end  of  the  combustion  chamber,  so  as  to 
expel  the  contents  mechanically,  was  used  with  success  on  the 
Atkinson  variable  stroke  gas  engine,  now  no  longer  manufac- 
tured, also  on  the  Diesel  engine,  but  it  is  the  least  economical 
procedure,  owing  principally  to  the  necessity  of  using  a  plane 
surface  cylinder  head  instead  of  one  of  segmental  profile,  and 
some  such  complicated  mechanical  devices,  as  were  used  in  the 
Atkinson  cycle.  The  fresh  air  method  requires  only  that  the 
crank  case  be  used  as  a  pump  chamber  for  the  air. 

Data  on  Scavenging  Cylinder — In  order  to  show  how 
that  the  burned  out  gases  in  the  clearance  operate  to  lower  the 
explosion  efficiency,  we  can  do  no  better  than  quote  again  from 
the  "Power  Quarterly"  treatise  already  mentioned.  Here  the 
following  occurs :  "The  difference  due  to  the  presence  of  burned 
gases  is  considerable.  A  mixture  of  9  to  I,  with  no  burned  gases 
present,  gives  a  rise  of  about  2,373  degrees ;  the  same  mixture, 
compressed  with  the  burned  gases  of  a  previous  explosion  in  a 
clearance  of  41  2-3  per  cent,  of  the  cylinder  volume  gives  a  rise 
of  only  about  1,843  degrees. 


212 


SELF-PROPELLED   VEHICLES. 


"The  resulting  temperatures  of  explosion  in  the  two  cases  do 
not  differ  so  greatly  as  the  rise  in  temperature,  because  the 
scavenging  engine  starts  from  a  lower  initial  temperature  and 
the  rise  during  compression  is  not  so  great.  For  example,  as- 
sume an  engine  with  3.4  compression  ratio,  running  scavenging 
with  an  initial  pressure  of  13.2  pounds  and  an  initial  temperature 
of  580° ;  and  suppose  a  similar  engine  running  plain,  with  13.2 
pounds  initial  pressure  and  600°  initial  temperature.  The  results 
are  compared  below  on  the  basis  of  a  9  to  I  mixture : 

Ordinary.     Scavenging. 

Initial  temperature    600  580 

Compression  temperature    921  858 

Rise  in  temperature  by  explosion 1*843  2,373 

Temperature  of  explosion 2,764  3*231 


FIG.  156.— Section  and  End  View  of  an  Efficient  American  Muffler.  The  muffler  consists 
of  a  series  of  chambers  formed  by  screens,  perforated  alternately  at  top  and  base,  so 
that  the  expanding  exhaust  gas  follows  the  course  indicated  by  the  arrows;  their 
passage  through  the  perforated  sections  serving  to  break  it  up  and  silence  the  noise 
due  to  its  pressure. 

"In  this  comparison  the  difference  in  the  rise  of  temperature 
is  nearly  29  per  cent.,  while  the  difference  between  the  explosion 
temperatures  of  the  two  engines  is  only  scant  17  per  cent.  A 
better  comparison  may  be  had  by  considering  the  pressures ; 
these  figure  out  as  follows : 

Ordinary.     Scavenging. 

Initial   pressure    , 13.2  13.2 

Compression  pressure    68.86  66.4 

Explosion  pressure  206.65  250.0 

"Thus,  the  scavenging  engine  shows  a  maximum  temperature 
about  17  per  cent,  higher  than  the  other  engine,  while  its  maxi- 
mum pressure  is  a  trifle  over  21  per  cent,  greater 

While  excessive  explosion  pressures  are  not  desirable,  it  is  clearly 


EXPLODING  THE  FUEL  CHARGE. 


213 


advantageous,  within  practical  limits,  to  increase  the  difference 
between  the  maximum  forward  pressure  and  that  of  compression, 
because  it  increases  the  area  of  the  indicator  diagram.  And  as 
this  result  is  obtained  by  scavenging,  without  consuming  any 
more  gas,  the  superiority  of  a  scavenging  engine  is  obvious." 

Exhaust  Losses  in  Heat  and  Power. — Having  followed 
the  operation  of  a  gas  engine  through  its  entire  cycle,  discussing 
the  several  conditions  of  efficiency  and  the  causes  of  lost  power, 
it  is  proper  to  touch  briefly  on  another  notable  cause  of  waste, 
which  is  frequently  mentioned  in  gas  engine  treatises.  This  re- 
fers to  the  expulsion  of  a  considerable  proportion  of  heat  and 
power  units  through  the  exhaust.  According  to  average  experi- 
ence, there  seems  to  be  no  practical  method  of  utilizing  any  of 


Fro.  157.— The  "  Loomis  "  Muffler.  The  exhaust  enters  the  central  tube  at  the  right-hand 
end,  passing  out  through  slits  shown  in  its  side  to  the  main  chamber,  where  it  is 
passed  through  a  number  of  lengths  of  tubing.  Leaving  these  it  emerges  to  atmos- 
phere through  another  set  of  tube  lengths. 

the  elements  thus  thrown  to  waste,  unless  we  resort  to  contriv- 
ances for  "compounding"  the  cylinders,  somewhat  after  the  plan 
of  the  double  and  triple  expansion  steam  engines.  The  principal 
reason  why  this  loss  may  not  be  avoided  is  that,  as  the  gas,  after 
explosion  may  not  be  expanded  so  as  to  stand  at  atmospheric 
pressure  on  the  completion  of  the  power  stroke^the  expansion 
line  then  standing  generally  about  or  above  the  figure  indicated 
for  compression  pressure— it  is  necessary  to  open  the  exhaust  be- 
fore the  completion  of  the  stroke.  This  opening  point  is  generally 
about  £  stroke.  Were  the  engine  otherwise  geared,  and  the  pis- 
ton allowed  to  receive  the  pressure  of  the  expanding  gas  through 
its  full  stroke,  the  gas  retained  until  that  time  would  not  exhaust 
fast  enough  to  avoid  buffing  the  piston  on  its  return  sweep, 
since  through  an  appreciable  distance  the  continued  expansion 
would  balance  the  rate  of  escape  through  the  exhaust  valve. 


214 


SELF-PROPELLED    VEHICLES. 


The  effect  of  this  would  be  to  check  the  speed  and  power  of  the 
engine,  with  the  result  of  absorbing  about  as  much  power  as 
would  on  the  other  plan  be  turned  to  waste. 

The  Variation  of  the  Curve  of  Expansion. — The  reason 
given  for  the  variation  from  the  compression  line  of  the  curve  of 
expansion  following  explosion  is  that  the  combustion  is  not  only 
not  instantaneous,  but  continues  during  the  greater  portion  of 
the  stroke,  thus  constantly  keeping  up  the  temperature  and  press- 
ure, which  would,  otherwise,  tend  to  fall  regularly  from  maxi- 
mum to  atmosphere.  Thus  the  expansion  line  does  not  meet 


FIG.  158.— Section  of  the  Atkinson  Cycle  Gas  Engine,  showing  the  varying  lengths  of  the 
strokes — from  the  top,  exhaust,  expansion,  compression,  suction;  also,  the  figure-of-8 
path  described  by  the  toggle-jointed  crank  connections,  and  the  path  of  the  crank. 

the  compression  line  at  the  end  point  of  the  stroke,  as  should  be 
the  case  under  theoretically  perfect  conditions,  with  the  result 
that  the  exhaust  valve  must  be  opened  before  the  completion  of 
the  stroke,  as  above  stated.  An  interesting  approximation  of  this 
standard  is  found  in  the  Atkinson  cycle  scavenging  engine,  which, 
on  account  of  certain  mechanical  peculiarities  of  construction,  is 
able  to  expand  the  charge  from  185  pounds  at  explosion  to  10 
pounds,  gauge,  at  the  completion  of  the  power  stroke.  In  this 
machine  the  piston  rod  is  connected  to  a  double  toggle  joint,  as 
indicated  in  the  accompanying  diagram,  with  the  result  that  the 
piston  makes  its  four  strokes  in  a  single  revolution  of  the  fly- 


EXPLODING   THE  FUEL    CHARGE. 


215 


wheel,  giving  a  suction  stroke  through  about  one-half  the  sweep 
length,  a  return  compression  stroke  to  a  point  about  5-6  the 
sweep,  an  impulse  stroke  from  that  point  clear  forward,  and  an 
exhausting  stroke  from  end  to  end  of  the  cylinder.  As  claimed 
in  a  published  description,  the  working  effects  are  that:  "The 
clearance  space  beyond  the  terminal  exhaust  position  of  the  pis- 
ton is  so  small  that,  practically,  the  products  of  combustion  are 
entirely  swept  out  of  the  cylinder  during  the  exhaust  stroke,  so 
that  each  incoming  charge  has  the  full  explosive  strength  due 
to  the  mixture  used. 

"It  is  also  possible  to  expand  the  exploded  charge  to  such  a 
volume  that  the  terminal  pressure  will  be  reduced  to  the  lowest 
possible  point,  and  that,  owing  to  the  purity  of  the  charge,  the 


>*! 


—  SUCTIOM a» X  i 

COMPRESSION    »  • 

r-txPAHSioM|-(iycy?A//yff  STROM) a» M 

'  — —  £(fC/iL  STftO^f  ) — ^ — M 


FIG.  159.— Indicator  Card  for  the  Atkinson  Variable  Stroke  Four- Part  "Two-Cycle"  Gas 

Engine. 

greatest  possible  pressure  will  be  attained  at  the  commencement 
of  the  expansion." 

The  accompanying  indicator  card  of  an  Atkinson  engine,  of 
18  I.  H.  P.,  working  at  130  revolutions  per  minute,  with  a  mean 
pressure  of  49  pounds,  shows  the  excellent  results  achieved  by 
thus  varying  the  length  of  the  several  strokes.  But  such  a 
procedure  is  impossible  in  the  ordinary  four-cycle  engine,  which 
finds  the  only  available  method  of  securing  approximately  com- 
plete combustion  in  varying  the  proportions  of  the  fuel  mixture, 
and  by  scavenging  the  cylinder. 

The  Ratio  of  Expansion. — As  may  be  readily  understood, 
the  practice  of  opening  the  exhaust  valve  at  about  J  power  stroke 
gives  one  reason  why  that  the  expansion  ratio  differs  so  greatly 


216  SELF-PROPELLED    VEHICLES. 

from  the  compression  ratio,  with  which,  theoretically,  it  should 
be  identical.  On  the  Atkinson  cycle  this  correspondence  is 
practically  realized,  but  with  engines  constructed  on  the  Otto 
cycle  it  represents  the  quotient  found  by  dividing  the  sum  of  the 
total  cylinder  content  (clearance  plus  piston  sweep)  and  that  por- 
tion of  the  stroke  and  clearance  content,  left  behind  the  piston 
at  the  moment  the  exhaust  opens,  by  the  cubic  content  of  the 
clearance.  This  may  be  expressed  by  the  following  formula: 


Er  = 


0  +  -JT-        Volume  of  Expansion 
B  Volume  of  Clearance 


in  which  Er  is  the  ratio  of  expansion. 

C  '  "  the  total  cylinder  content. 

B     "  the  combustion  chamber  or  clearance  content. 

n  "  the  numerator  expressing  the  portion  of  the  cyl- 
inder content  left  behind  the  piston  at  the  opening  of  the  ex- 
haust. 

Data  on  Losses  by  the  Exhaust. — In  the  process  of  ex- 
hausting, the  burned  gases  issue  from  the  cylinder;  first  place, 
largely  under  their  own  force  of  expansion,  which  continues 
down  to  atmospheric  pressure;  secondly,  after  the  change  of 
stroke,  under  the  force  of  the  returning  piston.  The  pressures 
and  temperatures  thus  voided  are,  of  course,  in  proportion,  first 
place,  to  the  figures  realized  in  explosion,  and,  secondly,  to  the 
expansion  ratio  of  the  particular  cylinder  under  test.  Both  are 
found  to  decrease  with  increasing  ratios.  Thus,  under  ordinary 
conditions  with  engines  driven  by  illuminating  gas,  an  explosion 
temperature  of  3,000  and  an  explosion  pressure  of  250  for  a  ratio 
of  3  give  an  exhaust  temperature  of  2,158  and  an  exhaust  pres- 
sure of  59.9 ;  for  a  ratio  of  3.5  they  give  2,060  and  49.0 ;  for  a  ratio 
of  4  they  give  1,979  and  41 -2 ;  for  a  ratio  of  5  they  give  1,851  and 
30.8 ;  for  a  ratio  of  6  they  give  1,752  and  24.3. 

In  order  to  fully  describe  the  situations  involved,  we  can  do  no 
better  than  to  quote  again  from  the  treatise  already  referred  to 
in  several  connections.  Here  we  have  it  that : 

"The  compression  ratio  ranges  in  present  practice  from  3  to  4 ; 
\vith  the  former  ratio  the  exhaust  pressure  is  never  less  than  35.7 
pounds,  and  with  the  latter  24.7  pounds,  absolute,  and  it  is  usually 


EXPLODING   THE  FUEL    CHARGE.  217 

around  45  pounds  for  one  and  30  for  the  other,  as  the  explosion 
pressure  is  generally  180  to  200.  So  that  there  is  a  waste  usually 
of  15  to  30  pounds  available  pressure  at  the  end  of  the  power 
stroke.  And,  as  the  explosion  temperature  is  almost  always 
around  2,500  and  is  frequently  near  3,000,  the  temperature  of 
the  exhaust  is  generally  from  1,600  to  1,900 — say  1,760  average, 
or  1,300°  by  thermometer  scale.  This  means  that  if  the  outdoor 
temperature  is  70°,  a  difference  of  1,230°  is  thrown  away.  And 
as  the  specific  heat  of  the  products  of  combustion  averages  .26, 
every  pound  of  exhaust  gas  emitted  at  1,300°  F.  into  an  atmos- 
phere of  70°  means  throwing  away  1,230  x. 26=  319.8  heat  units, 

or  319.8x778  =248,804  foot  pounds  of  energy 

"Suppose  we  assume  an  expansion  ratio  of  5.8,  in  order  to  get 
a  great  expansion,  and  a  compression  ratio  of  6.  Then  assume 
an  ordinary  engine,  because  the  effect  of  explosion  is  not  so  great 
and  a  mixture  of  12  volumes  of  air  to  I  of  gas,  because  that  is 
the  weakest  reliable  mixture.  Starting  with  the  highest  practi- 
cal initial  temperature,  660°,  and  the  lowest  practical  initial  press- 
ure, 13,  the  following  results  are  obtained: 

Pressure.    Temperature. 

Initial    13  660 

Compression    , 146  1*236 

Rise i,755 

Explosion 353  2,991 

Exhaust    35-9  i>765 

On  Compounding  Gas  Engine  Cylinders. — The  enormous 
waste,  as  indicated  by  the  figures  given  above,  which  show  that 
over  7.5  horse-power  per  pound  of  fuel  gas  goes  through  the  ex- 
haust valves,  is  a  good  argument  for  seeking  some  device  to 
utilize  at  least  a  part  of  this  lost  energy.  The  Atkinson  cycle 
engine,  as  described  above,  seems  to  fill  many  of  the  requirements 
in  this  respect  for  stationary  engines,  but  for  motor  carriage  pur-, 
poses  compounding  seems  to  be  the  most  available  system  at 
present  under  consideration.  The  subject  has  been  discussed  at 
considerable  length  in  magazines  devoted  to  motor  carriage  in- 
terests, and  an  engine  embodying  the  proposed  requirements  has 
been  constructed  by  Messrs.  Crossley  and  Atkinson  in  England. 
This  motor,  shown  in  an  accompanying  illustration,  consists 
briefly  of  three  cylinders — two  primary,  or  high  pressure,  be- 


218 


SELF-PROPELLED    VEHICLES. 


tween  which  is  a  secondary,  or  low  pressure,  cylinder.  The  vol- 
ume' of  the  low  pressure  cylinder  is  about  twice  that  of  either  of 
the  high  pressure  cylinders,  thus  allowing  the  exhaust  gas  to 
expand  very  nearly  to  asmospheric  pressure,  when  fed  into  it 
from  either  of  the  others.  The  crank  shaft  is  so  arranged  that, 
while  the  two  low  pressure  pistons  are  at  the  dead  end  of  the  in- 
stroke — the  one,  of  compression,  the  other,  of  exhaust,  for  exam- 
ple— the  low  pressure  piston  is  at  the  dead  end  of  its  out-stroke, 
or  power-stroke.  Thus  the  exhaust  gas  is  fed  to  the  low  press- 


t~t>     ii>..........a -39- 


FIG.  160.— Crossley  Three-Cylinder  Compound  Gas  Engine.  The  two  end  cylinders  are 
high  pressure;  the  central  one,  low  pressure.  The  exhaust  from  the  two  high-pressure 
cylinders  is  admitted,  alternately,  to  the  low-pressure  cylinder  by  the  piston  valve, 
operated  by  the  crank  and  rotating  shaft  shown  at  the  left.  The  exhaust  from  the 
low-pressure  cylinder  passes  upward  through  the  port  at  its  top. 

ure  cylinder  from  both  high  pressure  cylinders  alternately,  and 
it  performs  a  power-stroke  once  in  each  revolution  of  the  fly- 
wheel, always  alternately  to  either  of  the  others.  As  may  be 
seen  from  examination  of  the  drawing,  connection  between  the 
high  pressure  and  low  pressure  cylinders  is  had  by  means  of  a 
triple  piston  valve  moved  longitudinally  on  a  secondary  shaft  and 
so  arranged  that  pure  atmospheric  air  may  be  admitted  to  the 
centre  cylinder,  when  either  of  the  others  misses  fire.  Compound 


EXPLODING   THE  FUEL    CHARGE.  219 

gas  engines,  made  by  other  engineers,  have  the  cranks  geared 
at  a  little  over  one-third  of  the  total  revolution,  instead  of  at  180°, 
as  in  the  one  shown.  It  has  also  been  proposed  to  make  the  vol- 
ume of  the  low  pressure  cylinder  at  least  three  times  that  of  either 
of  the  others,  but  this  seems  excessive  from  the  fact  that  the 
expanding  gas  fed  into  it  would  expand  to  a  point  below  atmos- 
phere. The  editor  of  the  "Horseless  Age"  gives  a  formula  dem- 
onstrating this,  as  follows ; 

P  = 

in  which  P  is  the  initial  low-pressure  pressure,  V,  the  initial  low- 
pressure  volume,?1, the  final  pressure, at  the  end  of  the  low-press- 
ure power-stroke,  V1,  the  final  volume  at  the  same  point,  and  y, 
the  ratio  of  the  specific  heat  of  the  gas  at  constant  pressure  to  the 
specific  heat  at  constant  volume,  which  is  about  1.5  for  gasoline 
exhaust.  Then,  taking  as  the  value  of  P  the  average  of  55 
pounds,  absolute,  with  1-3  as  the  value  of  the  fraction  because  the 
ratio  of  the  cylinders  is  i  to  3,  we  have 

P    —  55    (  -   )        =     10.6  absolute. 


The  result  shows  a  pressure  of  about  four  pounds  below  atmos- 
phere, which,  although  indicating  a  very  complete  utilization  of 
exhaust  gas,  involves  a  cut-off  of  the  efficient  power  before  the 
completion  of  the  stroke,  unless  a  compound  gas  engine  be 
operated  with  some  kind  of  vacuum-producing  condenser,  such 
as  is  so  important  an  item  with  triple  and' quadruple  expansion 
steam  engines.  How  such  an  adjunct  to  a  gas  engine  would 
operate,  and  what  would  be  its  construction,  we  need  not  pause 
to  inquire  here. 

The  Advantages  from  Compounding. — In  addition  to  econ- 
omy in  heat  efficiency,  which  is  the  primary  object  of  compound- 
ing a  gas  engine,  two  other  important  ends  are  achieved.  In  the 
first  place,  the  muffler,  or  exhaust  silencer,  may  be  dispensed 
with ;  -since,  as  in  the  compound  steam  engine  the  highly  expand- 
ed exhaust  products  issue  to  the  air  without  noise.  This  is  a  de- 
cided advantage ;  for,  since  the  principle  of  a  muffler  involves  im- 


220  SELF-PROPELLED    VEHICLES. 

posing  obstacles,  so  as  to  break  up  the  full  force  of  the  gas  as  it 
expands,  it  furnishes  an  undesirable  back  pressure  that  absorbs  a 
goodly  part  of  the  output  power.  In  accompanying  diagrams  sev- 
eral types  of  efficient  muffler  have  been  shown,  but  as  the  ques- 
tion of  proportions  is  in  place  here  a  few  facts  will  be  given. 
As  indicated  by  Roberts,  the  formula  for  the  cubic  content  of  a 
muffler  best  calculated  to  save  power  gives  3.5  times  the  square 
of  the  cylinder  diameter  in  inches  multiplied  by  the  length  of  the 
piston  stroke  in  inches,  or 

M    =    3.5    D2   L. 

A  French  authority  states  that  an  engine  of  8  I.  H.  P.,  run- 
ning without  muffler,  gave  6.1  B.  H.  P.  at  967  revolutions  per 
minute,  but,  with  muffler,  gave  the  same  efficiency  only  on  1,012 
revolutions.  He  also  found  for  a  2.25  I.  H.  P.  engine  an  efficient 
output  of  2.16  at  2,015  revolutions  without  muffler,  and,  of  1.91 
at  2,057  revolutions  with  muffler,  claiming  a  loss  of  20  kilogram- 
meters,  or  145  foot  pounds  per  second. 

In  the  second  place,  a  compound  gas  engine  of  the  Crossley- 
Atkinson  type  presents  the  advantage  of  affording  a  steady  drive, 
£S  in  a  steam  engine,  thus  obviating  the  necessity  of  leaving  the 
fly-wheel  to  "store  up"  power  sufficient  for  three  idle  strokes.  It 
is  probable  that,  as  motor  carriage  construction  approaches 
greater  perfection,  the  subject  of  compounding  will  come  in- 
creasingly to  the  front  on  account  of  these  and  other  advan- 
tages. 


CHAPTER    EIGHTEEN. 

GAS    ENGINE    EFFICIENCY,    AND    ITS    OPERATIVE    CONDITIONS. 

Conditions  of  Operation:  flaximum  Efficiency. — Having 
now  set  forth  and  discussed  several  of  the  more  important  occa- 
sions of  lost  efficiency  in  gas  engines,  together  with  some  of  the 
methods  employed  to  neutralize  waste,  it  is  proper  to  consider 
briefly  the  conditions  of  efficiency  and  their  computation.  As 
may  be  readily  understood  from  the  facts  stated,  no  gas  engine 
can  realize  the  full  power,  which,  theoretically,  it  should  produce. 
Even  under  the  most  favorable  conditions,  with  the  observance 
of  all  rules  and  the  use  of  all  means,  mechanical  and  otherwise, 
to  conserve  energy,  it  must  fall  below  the  figures  reached  by  cal- 
culation. Thus,  as  given  by  several  writers  on  gas  engines,  there 
are  at  least  four  different  equivalents  of  the  word,  efficiency : 
Maximum  theoretical  efficiency,  actual  heat  efficiency,  mean  effi- 
ciency and  mechanical  efficiency. 

The  maximum  theoretical  efficiency  assumes  perfect  conditions 
and  a  perfect  indicator  card  diagram,  showing  an  output  of  power 
equal  to  the  figures  realized  by  the  highest  explosion  pressure, 
with  instantaneous  and  complete  combustion  and  effective 
adiabatic  expansion  to  atmosphere  during  the  power-stroke.  It 
is  estimated,  therefore,  as  the  difference  between  the  explosion 
temperature,  absolute,  and  the  initial  temperature,  absolute— 
which  is  to  say  the  number  of  degrees  rise  from  initial  to  explo- 
sion— divided  by  the  explosion  pressure.  Thus  it  may  be  ex- 
presse'd  as 

Rise   in    degrees          =     T"-T'     =     Efficiency< 
Explosion   temperature  T11 

This  formula  holds  good  because,  on  the  theory  of  the  perfect 
gas  engine,  the  gas,  after  explosion,  should  be  expanded  to  at- 
mosphere, with  the  utilization  of  every  unit  of  heat,  or  the  re- 
turn to  the  initial  temperature.  The  efficient  figure,  therefore,  is 
the  rise  from  initial  to  explosion. 

Thus,  assuming  an  initial  temperature  of  660°,  absolute,  and  an 

221 


222  SELF-PROPELLED   VEHICLES. 

explosion  temperature    of    3,000°,    absolute,    we    have,  by  the 
formula, 

2340 

=      .78 

3000 

as  the  percentage  of  theoretical  efficiency  under  such  high  tem- 
peratures. 

Another  formula  calculates  the  maximum  theoretical  efficiency 
as  the  quotient  of  the  initial  temperature  and  the  rise  in  degrees 
absolute  to  the  explosion  point.  Thus : 

=  .282  and  1— .282  =  .718  per  cent. 

In  either  case,  however,  the  figures  would  be  modified  by  the 
fact  that  the  specific  heat  of  all  gases  differs  between  the  condi- 
tions of  constant  volume  and  constant  pressure.  Thus  the  speci- 
fic heat  at  constant  volume  for  a  12  to  I  mixture  of  air  and  coal 
gas  is  .1803,  and  for  constant  pressure,  .2526.  Their  ratio  is 

.2526 
71803  ~~ 

Consequently,  to  obtain  the  most  exact  figures,  we  must  mul- 
tiply the  former  quotient  by  1.4  and  subtract  from  I,  as  before, 
to  discover  the  percentage.  Thus,  we  have  the  formula : 

1  —  14   66°    =   1   —  (1.4  X   .282  =  .3948)   =  .6052 
2340 

as  the  percentage. 

The  Actual  Heat  Efficiency. — Owing  to  various  causes, 
partly  mechanical,  partly  physical,  as  already  discussed,  even 
this  percentage  is  impossible  in  an  ordinary  four-cycle  engine ; 
since  contrary  to  the  theory  of  the  above  formula,  the  exploded 
gas  is  not  expanded  to  initial  pressure  and  temperature,  but  only 
to  a  much  higher  point  at  exhaust.  Instead,  therefore,  of  the 
above  formula,  we  divide  the  exhaust  temperature,  Fahrenheit, 
by  the  figure  for  internal  temperature  rise,  Fahrenheit,  multiply 
by  1.4  and  substract  product  from  unity.  Thus,  taking  1,500 
as  a  fair  average  temperature  at  exhaust,  we  have : 


GAS  ENGINE  EFFICIENCY.  223 

as  the  percentage  of  efficient  power  to  be  realized  from  an 
average  gas  engine  under  most  favorable  conditions.  The  maxi- 
mum theoretical  efficiency,  therefore,  is  impossible  in  practice, 
even  under  ideal  conditions ;  since  it  assumes  that  the  expansion 
line  of  the  indicator  diagram  is  perfectly  adiabatic,  which  is  to 
say,  indicating  an  expansion  without  loss  or  gain  of  heat  units, 
to  atmosphere.  The  figures  are  valuable,  most  largely,  as  indi- 
cating the  necessary  limitations  of  gas  engine  operation  and  con- 
struction. Some  of  the  best  gas  engines,  however,  give  an  indi- 
cated power-output  of  30  per  cent,  and  over,  according  to  claims 


FIG.  161.— The  Duryea  Three-Cylinder  Gasoline  Vehicle  Engine,  with  half  the  crank  case 
sheathing  removed,  showing  cranks,  crank  shaft,  cam  shaft,  and  working  parts. 
The  three  cylinders  have  common  supply  and  exhaust  tubes:  the  charge  is  controlled 
by  a  single  throttling  link,  shown  at  the  top,  and  the  igniting  circuit  has  three  bridges 
for  the  three  cylinders 

—  some  assert  slightly  higher  figures — but,  even  with  this  low 
average  the  gas  engine  is  superior  to  the  steam  engine. 

Testing  by  the  Pyrometer — The  formulae  just  given  illustrate 
one  very  essential  point  in  gas-engine  operation,  which  is  that, 
given  the  temperature,  absolute,  at  the  moment  of  exhaust,  the 
efficiency  of  the  working  cycle  may  be  approximately  estimated ; 
always,  of  course,  allowing  due  value  to  the  heat  losses  through 
the  cylinder  walls,  and  otherwise,  as  above  discussed.  The  heat 


224  SELF-PROPELLED   VEHICLES. 

of  exhaust  averages  between  1,500°  and  1,900°,  absolute,  ac- 
cording to  the  compression  ratio,  which  determines  the  range  of 
temperature  rise  at  explosion ;  according  to  the  expansion  ratio, 
which  determines  the  range  of  effective  heat  and  power,  and, 
consequently,  according  to  the  temperature  of  explosion.  Of 
course,  such  high  temperatures  may  not  be  determined  by  an 
ordinary  thermometer ;  for,  since  the  vaporizing  point  of  mer- 
cury is  at  675°  Fahrenheit,  no  rise  beyond  that  could  be  ade- 
quately measured.  Accordingly,  the  device  used  is  that  known 
as  a  pyrometer,  one  form  of  which  consists  of  an  electric  circuit 
containing  a  source  of  current,  a  galvanometer  and  an  iron  tube, 
enclosing  a  contact  of  an  electrode  of  platinum  and  an  electrode 
of  iridium.  When  it  is  desired  to  determine  the  temperature  of 
a  given  point  ^or  body  the  iron  tube  is  placed  thereat,  and  the 
heat,  causing  the  enclosed  platinum  and  iridium  to  expand,  in- 
creases the  electrical  pressure  of  the  contact.  The  principle  in- 
volved is  that  by  increasing  the  pressure  in  this  manner  at  any 
part  of  the  circuit  increases  the  total  strength  of  the  conducted 
current.  Thus,  the  relative  increase  in  this  respect  may  be 
measured  in  the  galvanometer,  whose  readings,  within  thermo- 
metric  range,  have  already  been  determined  for  several  known 
temperatures,  enabling  the  discovery  of  the  ratio  on  which  the 
current  conductivity  of  the  circuit  increases  with  temperature  rise 
per  degree.  There  are  several  other  varieties  of  pyrometer, 
based  on  as  many  different  physical  and  mechanical  properties 
of  matter,  but  the  one  described — it  is  known  as  Chatelier's  pyro- 
meter after  its  inventor — seems  to  be  the  most  philosophic  and 
reliable. 

Heat  Efficiency:  Theoretical  and  Practical. — From  the  facts 
thus  far  set  forth  it  may  be  understood  that  the  actual  heat  effi- 
ciency, which  represents  "the  ratio  of  heat  turned  into  work  to  the 
total  heat  received  by  the  engine,"  furnishes  the  percentage  on 
which  is  based  the  calculations  for  "indicated  horse  power" 
(I.  H.  P.).  But,  on  account  of  the  unavoidable  waste  of  heat,  in 
the  first  place,  and  of  power,  in  the  second  place,  in  producing 
and  maintaining  the  conditions  of  operation  within  the  cylinder — 
in  keeping  the  temperature  within  operative  limits,  and  in  over- 
coming the  physical  inertia  of  the  moving  parts — the  indicated 
horse  power  is  always  much  greater  than  the  delivered  horse 


GAS  ENGINE  EFFICIENCY.  225 

power  (D.  H.  P.)  or  brake  horse  power  (B.  H.  P.),  when  both 
are  stated  in  terms  of  heat  units  consumed.  Owing  to  the  physi- 
cal properties  of  gases  and  to  the  conditions  of  waste,  which  re- 
duce the  expansion  line  from  the  theoretical  adiabatic  to  a  figure 
very  different,  the  total  efficiency,  as  we  have  seen,  falls  from  72 
per  cent,  to  26  per  cent.  The  greatest  possible  available  percent- 
age, however,  due  to  the  nearest  practicable  approach  to  ideal 
conditions,  would  represent  a  mean  between  these.  Conse- 
quently, we  may  derive  the  mean  theoretical  efficiency,  as  the  ratio 
between  the  actual  and  the  maximum  figures,  which  gives  us : 

Indicator  reading          26 

=  _  =.361, 


Theoretical  efficiency        72 

as  the  figure  representing  the  greatest  possible  utilization  of  heat 
in  the  operation  of  a  gas  cylinder. 

flechanical  Efficiency  in  Heat  Units  — Similarly  also,  the 
fourth  head  of  efficiency,  the  mechanical  efficiency,  of  a  gas  engine, 
represents  the  ratio  between  the  delivered  horse  power,  as  found 
by  Prony  brake  or  dynamometer,  and  the  indicated  horse  power, 
the  difference  in  practice  being  the  power  lost  by  general  internal 
friction  of  the  engine.  Thus,  if  the  indicated  horse  power  is  10 
and  the  delivered  horse  power  is  8,  the  ratio  is  found  as  follows : 

D.H.P.        8 

=  —  =  .80. 

I.H.P.        10 

To  state  this  in  terms  of  heat  expended,  we  find  that  one  horse 
power  is  33,000  foot-pounds  per  minute,  and  that  778  foot-pounds 
equals  one  thermal  unit,  which  equation  expresses  the  mechanical 
equivalent  of  heat.  Whence,  one  horse  power  per  minute  equals 
42.42  thermal  units,  which  is,  by  the  hour  2,545  thermal  units. 
Then  10  H.  P.  equals  25,450  thermal  units  and  8  H.  P.  equals 
20,360  thermal  units.  Whence  we  have : 

20360 

-  =  .80. 
25450 


226  SELF-PROPELLED   VEHICLES. 

If,  however,  10  H.  P.,  or  25,450  B.  T.  U.  per  hour  be  assumed 
equivalent  to  the  I.  H.  P.  of  a  given  engine,  which  is,  as  we  have 
seen,  26  per  cent,  of  the  total  fuel  efficiency  supplied  to  the  en- 
gine, we  have  it  that  the  total  theoretical  value  of  the  fuel  should 
be  97,884.61  B.  T.  U.,  or  38.46  H.  P.  According  to  a  noted 
authority,  the  average  of  a  number  of  tests  of  gas  engines  is  as 
follows : 

To  the  jacket  water 52  per  cent. 

To  loss  in  the  exhaust 16     "       " 

To  loss  in  radiator,  etc 15     "       " 

To  useful  work  (D.  H.  P.) 17     "       " 


FIG.  162.— Four-Cylinder,  10  H.  P.  "  Buffalo"  Gasoline  Engine  for  Motor  Vehicle  Use.  The 
gearing  of  this  motor  renders  it  non-vibrating,  as  guaranteed,  while,  by  the  "shifting- 
spark"  system  of  governing,  the  speed  may  be  varied  from  100  to  1,500  R.  P.  M.  with- 
out changing  the  motion  of  the  valves.  This  is  an  exceedingly  flexible  system  of 
governing.  The  cylinder  head  is  water- jacketed;  the  firing  stroke  in  the  four  cylin- 
ders follows  consecutively,  thus  securing  perfect  balance:  the  inlet  valves  are  posi- 
tively operated,  thus  enabling  a  wide  range  in  adjusting  fuel  charge  ratios.  On  ac- 
count of  the  four-cylinder  positive  igniters,  the  engine  is  very  easy  to  start. 

This  shows  a  total  of  83  per  cent,  lost  for  efficient  mechanical 
work,  or  useful,  at  best,  only  for  maintaining  necessary  interior 
conditions.  Accepting  these  figures  as  fairly  typical,  we  find  for 
10  I.  H.  P.,  or  26  per  cent.,  a  total  of  97,884.61  thermal  units,  or 
38.46  H.  P.  by  the  hour,  theoretically  fed  to  the  cylinder  in  shape 


GAS  ENGINE  EFFICIENCY.  227 

of  fuel  mixture.    Giving  the  other  quantities  their  proper  thermal 
and  mechanical  equivalents,  we  have  : 

52^  =  50899.9972  B.  T.  U.  =19.9992  H.  P. 
=  15661.5376  B.  T.  U.=  6.1536  H.  P. 
=  14682,6915  B.  T.  U.=  5.7890  H.  P. 
=  16640.3837  B.  T.  U.=  6.5382  H.  P. 


100       97884.6100  38.4600. 

This  example,  drawn  from  actual  averages,  represents  only  6J 
B.  H.  P.  on  10  I.  H.  P.,  but  in  general  practice  the  figures  are 
usually  given  as  about  8  to  10. 

Another  authority,  as  quoted  by  several  writers,  finds  the  fol- 
lowing results  from  a  series  of  experiments  with  a  125  H.  P.  gas 
engine :  At  full  load  26  per  cent,  of  the  heat  energy  becomes 
converted  into  mechanical  energy,  44  per  cent,  lost  through  the 
exhaust  and  by  radiation  and  30  per  cent,  absorbed  by  the  jacket 
water.  At  three-quarter  load,  the  figures  become  25,  38  and  37 
per  cent,  respectively;  at  one-quarter  load,  18,  28,  54,  and,  when 
running  free,  10,  32  and  58  per  cent.  These  figures  show  that 
the  percentage  of  loss  through  the  exhaust  increases  as  the  jacket 
loss  decreases.  Other  recorded  tests  show  similar  figures. 

To  discover  the  calorific  value  of  a  gas  by  the  cubic 
foot,  or  by  any  other  unit  of  cubic  or  weight  measure,  the  fol- 
lowing formula  has  been  laid  down  for  determination  by  the  cubic 
amount  consumed  in  raising  the  temperature  of  water  by  the  de- 
gree: 

W  T 

H=--, 
G 

in  which  H  is  the  calorific  value  ; 

W  "     "    quantity  of  water  by  volume ; 
T    "     "    difference  in  temperature  of  the  water  sup- 
plied and  the  water  heated ; 
G    "     "    quantity  of  gas,  in  cubic  feet,  required  to  raise 

the  water  to  the  given  temperature. 

Supposing  that  in  a  given  case,  W  is  equal  to  i  liter  (.22  gal- 
lon) ;  T  is  equal  to  18,  or  the  difference  between  27°,  the  acquired 
temperature,  and  9°,  the  initial  temperature  of  the  water ;  and  G, 


228  SELF-PROPELLED    VEHICLES. 

as  measured  by  a  gas  meter,  or  other  suitable  method,  equals  .190 
cubic  foot.  Then  : 

1X18 

H'=—    —=94.73  thermal  units. 
.190 

as  the  gross  calorific  value  per  cubic  foot  of  the  particular  mix- 
ture of  gas  and  air  used  for  the  experiment.  The  net  value  is 
usually  estimated  at  about  15  per  cent,  of  the  gross  for  most 
fuel  gases,  as  found  by  the  average  of  calorimeter  tests. 
Whence,  since  15  per  cent,  of  94.73  is  about  14.21,  the  net 
value  here  is  80.52  calories,  which  indicates  the  percentage  of 
heat  units  actually  efficient  in  raising  the  temperature  of  the 
water. 

Calorific  Value  of    Fuels.  —  -As  given  by  reliable  authorities, 
the  calorific  value  of  several  common  hydrocarbon  fuels,  as  ex- 
pressed in  thermal  units,  is  as  follows  : 

Per  Pound.     Per  Cubic  Foot. 
Marsh  gas  (C  H4)  ................   23,594  1,051 

Benzine  (C°  H°)  ..................    18,448 

Acetylene  (C2  H2)  ..........  ......  21,492  868 

Ethylene  (C2  H4)  .................   21,430  1,677 

Natural  gas  .....................  ---  4$o  to  590 

Illuminating  coal  gas  ........  .....   -  620  to  950 

Water  gas  (average)  .............   -  7IQ 

Having  ascertained  these  facts,  we  are  prepared  to  determine 
the  thermal  efficiency  of  the  engine,  or  the  ratio  of  heat  utilized, 
as  compared  with  the  total  heat  equivalent  of  the  fuel  absorbed. 
For  this  purpose  the  following  formula  is  given  by  Goldingham  : 

42.63X60 


cx 

in  which  C  expresses  the  fuel  consumption  per  B.  H.  P.  per  hour 
in  pounds,  and  X  the  calorific  value  of  the  fuel  per  pound  in 
thermal  units. 

Although  the  constant  42.63  should  vary  somewhat  according 
to  the  figures  for  heat  and  power  equivalents  as  used  by  other 
authorities  we  may  use  this  formula  for  approximate  figures.  By 
the  table  of  percentages  given  above,  we  find  that  for  each  B.  H. 


GAS  ENGINE  EFFICIENCY.  229 

P.,  or  2545  B.  T.  U.,  5.88  H.  P.,  or  14964.60  B.  T.  U.,  are  ex- 
pended. Since  gasoline  contains  21,900  B.  T.  U.  per  pound,  we 
find  that  this  average  figure  gives  us  0.683  pounds  fuel  consump- 
tion per  B.  H.  P.  per  hour.  Then,  by  the  formula,  we  have : 

42.63x60       2557-80 
'  E=  -  -  =±  —      -=0.1687. 

.683x21900       15157.7 

as  the  approximate  thermal  efficiency  percentage.  This  figure 
agrees  with  the  average  percentage  for  B.  H.  P.,  given  above, 
and,  as  may  be  seen,  can  be  found  by  knowing  simply  the  rate  of 
fuel  consumption  and  the  B.  T.  U.'s  per  pound. 

Determining  Calorific  Values. — Knowing  the  specific  heat  of 
a  given  gas  at  constant  volume,  the  calorific  value  in  thermal 
units  may  be  discovered  as  follows,  in  order  to  estimate  the  ther- 
mal efficiency  of  an  engine  : 

H  =  C  (T-t). 

In  this  formula  H  is  the  calorific  value  in  thermal  units ;  C,  the 
specific  heat  at  constant  volume ;  T,  the  temperature  of  explosion, 
and  t,  the  initial  temperature.  The  specific  heat  for  a  9  to  i  mix- 
ture of  air  and  coal  gas  being  0.1846;  a  typical  explosion  tem- 
perature 2,764°,  absolute,  and  an  average  compression  tempera- 
ture, 921°,  we  have  340.21  thermal  units  per  pound  of  the  initial 
charge,  which  is  equivalent  to  264683.38  foot-pounds,  and 
264,683.38 

-  =  8.02  H.  P. 
33,000 

Determining  the  Explosion  Pressure — The  maximum,  or 
explosion,  pressure  of  a  gas-engine  is  equal  to  the  ratio  between 
the  compression  and  maximum  temperatures  multiplied  by  the 
compression  pressure.  Thus : 

Ct 

xCp  =  Bp. 

Et 

Substituting  the  values  given  above  for  a  given  engine,  we 
have 

(2764       \ 
=3  1x68.86=206.58  pounds, 
921        / 


230  SELF-PROPELLED    VEHICLES. 

which,  as  may  be  seen,  is  the  same  as  formerly  given  in  Chapter 
XXIV.  (page  348): 


T'. 

In  order  to  estimate  the  mechanical  efficiency  of«a  given  en- 
gine we  must,  as  shown  above,  know  the  delivered  horse  power. 
While  there  are  numerous  ways  of  calculating  this,  the  simplest 
and  readiest  formula  is  as  follows  : 

D2LR 

-  =D.  H.  P. 

18,000 

which  means  that  the  square  of  the  piston  diameter  in  inches  is  to 
be  multiplied  by  the  length  of  the  stroke  in  inches  and  the  number 
of  revolutions  per  minute  of  the  fiy-wheel,  and  the  product  divided 
by  18,000.  This  denominator  is  given  by  Roberts  for  a  four- 
cycle gasoline  engine.  For  ordinary  four-cycle  gas-engines  the 
figure  is  19,000.  For  two-cycle  engines  operated  by  gasoline  the 
denominator  is  given  as  13,500;  for  other  types,  as  14,000. 

To  apply  this  formula  we  will  take  a  highly  efficient  three  cyl- 
inder gasoline  vehicle  motor  with  proportions,  as  follows  :  The 
piston  diameter  is  4.5  inches  ;  the  stroke  is  4.5  inches  ;  the  number 
of  revolutions  per  minute  is  600.  Then,  substituting,  we  have  : 

20.25x4.5x600        54,675 
-  -  =  --  =  3.03  H.  P. 
18,000  18,000  • 

Calculating  for  the  three  cylinders  we  have  the  formula  : 

D2LRN 

-  =  H.  P. 
18,000 

in  which  N  is  the  number  of  cylinders.    Whence: 
54,675x3 


18,000 


=  9.11  H.  P. 


This  figure  is  a  good  average  for  the  formula,  although 
as  the  writer  is  assured  by  the  manufacturer  of  the  engine, 
ioj  D.  H.  P.  has  been  obtained  by  actual  brake  tests. 


GAS  ENGINE  EFFICIENCY.  231 

Similarly,  on  the  basis  of  these  figures,  we  may  calculate  the 
mechanical  efficiency  per  cubic  inch  of  piston  displacement,  or 
fuel  capacity,  as  follows : 

33,000x3.03  99,990 

=  4,658. 


15. 904  X  4. 50  X  300        21,470. 4 

In  this  equation,  15.904  represents  the  area  in  inches  of  a  4.5 
inch  piston ;  4.50  represents  the  length  of  the  stroke ;  300  the 
number  of  explosions  per  minute.  The  numerator,  representing 
the  figure  for  3.03  H.  P.  in  terms  of  foot-pounds  per  minute,  is 
divided  by  the  product  of  the  denominator  terms  to  give  the  foot- 
pounds per  cubic  inch  of  stroke  space.  The  result  is  verified  by 
performing  the  following  operation  : 

15. 904  X  4. 50  X  300  X  4. 65        100009. 1232 

-  = =  3.03, 

33,000  33,000 

in  which  the  figure  for  foot-pounds  is  multiplied  by  the  cubic 
content  in  question  and  the  number  of  efficient  strokes  per  min- 
ute in  order  to  obtain  an  expression  in  the  numerator,  as  in  the 
denominator,  for  foot-pounds  per  minute.  The  result  of  the  in- 
dicated division  is  the  delivered  horse  power. 


CHAPTER    NINETEEN. 

ON   ESTIMATING  THE   HORSE-POWER   OF   GAS   ENGINES. 

Conditions  of  Efficient  Operation. — Following  along  the 
lines  so  far  laid  down,  we  find  six  conditions  of  high  efficiency : 
i.  The  fuel  mixture  should  be  carefully  proportioned,  in  order 
to  enable  rapid  ignition  and  full  utilization  of  heat.  2.  The  press- 
ure of  compression  should  be  high,  in  order  to  enlarge  the  range 
of  temperature  rise  at  explosion.  3.  The  wall  surface  of  the  clear- 
ance, or  combustion  chamber,  should  be  as  small  as  practicable, 
in  proportion  to  its  required  volume,  in  order  to  lower  the  ab- 
sorption of  the  heat  of  combustion  and  raise  the  mean  wall  tem- 
perature, facilitating  compression.  4.  The  stroke  should  be  as 
short  as  is  consistent  with  good  design,  in  order  to  reduce  the 
wall  surface  to  which  the  expanding  gas  is  exposed,  with  conse- 
quent economy  of  heat  and  power.  5.  The  speed  of  the  piston 
should  be  high,  in  order  to  transform  the  heat  into  work  with 
the  greatest  possible  rapidity,  also  reducing  the  period  of  contact 
between  the  expanding  gases  and  the  cylinder  walls.  6.  The 
temperature  and  rate  of  circulation  of  the  jacket  water  should  be 
adjusted,  in  accordance  with  careful  observation,  in  order  that 
the  temperature  of  the  cylinder  may  be  kept  within  the  required 
limits,  without  also  absorbing  too  great  a  quantity  of  heat. 

The  Time  Element  in  Power  Estimates — In  the  determina- 
tion of  horse-power  the  time  element  is  an  important  item  in  all 
formulae.  This  is  true  because  the  power  to  be  calculated  pro- 
duces motion  and  is  not  simply  a  static  pressure  to  be  measured 
in  terms  of  pounds  weight.  In  calculating  for  a  gas-engine,  also, 
it  is  important  to  remember  that  the  power  efficiency  increases 
with  the  rate  of  motion,  being  expressed  in  terms  of  revolutions 
per  minute  of  the  fly-wheel  or  crank  shaft.  Thus,  a  given  engine 
running  with  low  gas  supply  or  high  load  may  be  able  to  rotate 
the  fly-wheel  only  200  times  per  minute,  while,  with  full  gas  sup- 
ply, or  at  average  load,  it  can  produce  as  many  as  2,000  revolu- 
tions per  minute.  Furthermore,  the  available  power  decreases 
as  does  the  number  of  revolutions  per  minute,  while,  as  has  al- 


ESTIMATING  HORSE-POWER.  233 

ready  been  indicated,  the  rate  of  gas  consumption  per  unit  of 
work  is  increased.  Thus  it  is  important  to  know,  in  making  es- 
timates for  horse-power,  whether  the  engine  in  question  is  run- 
ning free  or  under  load.  This  fact  is  generally  specified  in  reports 
on  engine  power  and  operation,  and  is  considered  in  several 
formulae. 

Engine  Dimensions  in  Power  Estimate. — Next  to  this,  the 
most  important  consideration  refers  to  the  dimensions  of 
the  piston  and  cylinder  and  the  length  of  the  stroke.  For, 
since  these  figures  indicate  the  power  capacity  of  the  en- 
gine, in  point  of  the  quantity  of  fuel  consumed,  and  the 
power  developed  by  explosion,  as  acting  on  the  reciprocating 
parts,  they,  together  with  the  ascertained  rate  of  motion,  are  in 
ratio  to  a  figure  equivalent  to  an  average  ratio  between  the  opera- 
tive dimensions  of  the  cylinder — these  are  given  above  in  Rob- 
erts' formula  for  D.  H.  P. — and  the  delivered  horse-power.  For 
four-cycle  gasoline  engines  this  average  denominator  is  given  as 
18,000,  and  the  figures  resulting  from  the  indicated  division  are 
average  ones.  The  formula  is  further  verified  in  the  fact  that  the 
piston  diameter  and  length  of  stroke  are  in  discoverable  propor- 
tion to  the  D.  H.  P.  and  the  number  of  revolutions  of  the  fly- 
wheel. So  that  an  engine  giving,  say,  35  D.  H.  P.  at  600  revolu- 
tions per  minute,  with  a  fuel  whose  thermic  value  is  known,  must 
have  a  certain  diameter  of  piston  and  length  of  stroke.  These 
proportions  need  not  be  further  specified  here. 

The  flean  Effective  Pressure.  —In  making  more  definite 
calculations  on  the  power  of  a  gas-engine  there  are  four  points  to 
be  considered:  I.  How  great  is  the  mean  effective  pressure  per 
square  inch  on  the  piston  during  the  power  stroke?  2.  What  is 
the  area  of  the  piston?  3.  What  is  the  length  of  the  stroke?  4. 
What  is  the  number  of  explosions  per  minute?  The  ratio  be- 
tween the  product  of  these  factors  and  33,000  gives  the  I.  H.  P. 
per  minute.  Thus : 

Pressure  X  area  X  stroke  X  E.  P.  M. 

— =  I.  H.  P. 

33,000 

To  reduce  this  ratio  to  a  practical  formula  we  take  the  product 
of  the  mean  effective  pressure  of  the  power  stroke;  by  the  area 


234  SELF-PROPELLED    VEHICLES. 

of  the  piston  in  square  inches;  by  the  length  of  the  stroke  in  feet ; 
by  the  number  of  explosions  per  minute,  and  divide  by  33,000, 
which  figure  expresses  the  number  of  foot-pounds  per  minute  per 
horse-power.  Thus : 

PA  SE 

-=  I.  H.  P. 
33,000 

Taking  the  figures  for  the  gasoline  engine  calculated  above, 
which  gave  3.03  D.  H.  P.,  we  have : 

80  X 15. 904  X  .375  X  300       141036 

-  =  -         -  =4.27  I.  H.  P. 
33,000  33,000 

In  this  operation  the  figure  80  represents  a  fair  average  of  mean 
effective  pressure  for  high-grade  gasoline  engines  under  25 
H.  P.;  15.904  is  the  area  in  square  inches  of  a  piston  4.5  inches 
diameter;  .375  is  the  expression  in  feet  for  4.5  inch  stroke,  and 
300  the  number  of  explosions  per  minute.  The  result,  4.27  I.  H. 
P.,  is  a  fairly  proportionate  figure  for  indicated  horse-power  of 
this  engine,  since,  taking  3.03  as  17  per  cent.,  it  is  equivalent  to 
22.8  per  cent.  In  order  to  get  anything  like  exact  figures,  it  is 
necessary  to  determine  the  mean  effective  pressure,  which  can 
be  most  readily  discovered  with  an  indicator  tracing,  such  as  has 
been  depicted  above.  The  methods  of  measuring  are  either  by 
ruling  ordinatcs  at  right  angles  to  the  atmospheric  or  base  line  of 
the  diagram  and  taking  .the  average  of  their  length,  or  by  use  of 
an  instrument  called  the  planimeter. 

Estimating  by  the  Indicator  Diagram  — As  may  be  under- 
stood from  the  term  itself,  the  mean  effective  pressure  is  an  aver- 
age expression  for  the  degree  of  pressure  in  pounds  brought  to 
bear  upon  the  piston  of  a  cylinder  during  the  power  stroke.  It 
has  been  well  defined  as  "the  difference  between  the  average 
e-auge  pressure  shown  by  the  expansion  line  and  that  shown  by 
the  compression  line,  minus  the  back  pressure  of  charging  or  suc- 
tion." As  all  these  operations  are  depicted  on  the  indicator  dia- 
gram an  average  of  its  proportions  will  yield  the  desired  result. 
On  the  method  of  calculating  bv  ordinates  we  proceed  as  fol- 
lows: A  number  of  parallel  equidistant  lines  are  ruled  on  the  dia- 
gram at  right  angles  to  the  base  line,  and  their  lengths  measure^ 


ESTIMA  TING   HORSE-PO  WER. 


235 


between  the  points  where  they  intersect  the  compression  and  the 
expansion  curves.  The  lengths  thus  found  are  added  together 
and  the  sum  divided  by  the  number  expressing  their  number,  in 
order  to  obtain  an  expression  for  the  average  length.  This  re- 
sult is  then  multiplied  by  the  pressure  of  explosion  as  recorded 
by  the  indicator  tracing.  If,  then,  the  average  length  of  the  ordi- 
nate  lines  is  two  inches  and  the  indicated  pressure  at  explosion 
is  300  pounds,  the  result  would  show  a  mean  effective  pressure  of 
600  inch-pounds  or  50  foot-pounds. 

A  simpler  method  is  to  find  the  mean  ordinate  of  the  diagram 
by  the  following  process :  Find  the  centre  of  the  diagram  figure 


FIG.  163.— Recording  Mechanism  of  a  Typical  Planimeter.  D  is  the  graduated  drum, 
divided  into  10  numbered  sections,  each  representing  1  square  inch,  and  10  interme- 
diate points,  each  equal  to  1-10  square  inch.  E  is  the  vernier,  which  is  divided  into  10 
equal  parts,  each  representing  1-100  inch.  The  wheel,  G,  records  the  number  of  revo- 
lutions of  the  drum,  D,  each  of  its  graduations  being  equivalent  to  10  square  inches, 
as  measured  at  the  post,  J.  The  measurement  on  the  positions  shown  gives  10  on 
disc,  G;  4  on  the  roller,  D,  which  is  the  last  number  passing  zero  on  the  vernier;  7-10 
for  the  smaller  graduations  on  D,  as  shown  by  line,  a,  at  zero  on  the  vernier;  and  3 
on  the  vernier,  as  representing  the  scale  point  on  the  vernier  opposite  to  the  nearest 
number  on  D.  The  result  is,  therefore,  14.73  square  inches. 

on  the  base  line ;  erect  a  line  perpendicular  to  the  base  from  that 
point;  draw  another  line  from  the  base  so  that  it  touches  the 
expansion  line  at  about  the  point  of  exhaust  valve  opening,  at 
such  an  angle  that  the  two  parts  on  either  side  of  the  centre  line 
will  be  equal,  measuring  from  a  perpendicular  on  the  explosion 
line  on  the  one  side,  and  from  another  touching  the  "toe"  of  the 
tracing  on  the  opposite  side.  The  portion  of  the  centre  line  thus 
laid  off  by  intersection  is  the  mean  ordinate,  which,  multiplied 
by  the  indicated  pressure,  gives  the  M.  E.  P, 


236  SELF-PROPELLED    VEHICLES. 

Calculating  Diagrams  by  Plan i meter.— A  more  exact  method 
is  by  the  use  of  the  planimeter,  one  form  of  which  is  shown  in  an 
accompanying  figure.  Briefly,  it  consists  of  two  arms  pivoted 
together.  One  of  them  is  arranged  to  be  secured  to  the  board, 
the  other  carries  a  tracing  point  on  the  free  end  and  a  graduated 
wheel  arranged  to  indicate  square  inches  and  tenths  of  an  inch 
and  a  vernier  to  indicate  hundredths.  Having  secured  the  instru- 
ment to  the  board  in  such  a  manner  that  the  tracer  may  be  set 
upon  the  lines  of  the  diagram,  the  graduated  wheel  is  adjusted 
so  that  the  point  registers  zero.  Then,  moving  the  tracing  point 
over  the  entire  line  of  the  diagram  in  the  same  direction  as  the 
hands  of  a  watch,  the  wheel  is  made  to  travel  accordingly,  and 
to  register  the  area  of  the  circumscribed  space.  If,  now,  the 
largest  figure  on  the  graduated  wheel  is  2,  and  the  number  of 
graduations  thereafter  passing  zero  on  the  vernier  be  6  and  the 
opposite  graduation  on  the  vernier  be  4,  we  have  the  figure  2.64 
as  the  area  of  the  diagram  in  square  inches.  This  figure  should 
then  be  divided  by  the  extreme  length  of  the  diagram,  which 
may  be  taken  as  3.2  inches,  which  gives  the  quotient  0.821875 
as  the  average  height  of  the  diagram.  This  figure  multiplied  by 
the  scale  of  the  spring,  used  in  the  indicator  making  the  diagram, 
gives  the  figure  for  mean  effective  pressure.  If  this  figure  be  40, 
for  example,  we  have  as  the  result  32.88,  as  the  expression  for 
mean  effective  pressure.  From  this  it  may  be  understood  that 
the  size  of  the  diagram,  or  the  length  of  the  circumscribed  line- 
varies  according  to  the  strength  of  the  spring  geared  to  the  trac- 
ing pencil,  and,  according  to  the  engine  pressure  bearing  upon 
that  spring.  Thus  a  weak  spring  with  a  moderate  pressure  would 
give  a  very  large  diagram,  while  a  strong  spring  and  a  high  pres- 
sure would  give  one  no  larger.  Thus  the  spring  strength  or 
scale  is  an  item  in  calculating  the  effective  pressure  of  the  engine 
giving  the  diagram. 

The  indicator  is  fully  explained  in  the  chapter  on  steam. 

Determining:  the  Speed. — Knowing  tlie  mean  effective  press- 
ure of  the  engine,  the  only  undetermined  element  in  the  above 
formula  is  the  speed,  expressed  as  revolutions  per  minute  of  the 
fly-wheel,  which  being  halved  gives  the  number  of  explosions 
per  minute  for  a  four-cycle  engine.  The  readiest  method  is  to 
test  with  a  tachometer  (speed-meter),  an  instrument  consisting  of 


ESTIMATING  HORSE-POWER. 


23T 


a  rod  which  is  pressed  against  the  end  of  a  rotating  shaft,  so  as 
to  be  rotated  with  its  motion,  and  record  the  number  of  such 
revolutions  per  given  time  on  a  dial. 


FIG.  164.— Method  of  Averaging  a  Diagram  with  one  Type  of  Planitneter. 


The  pin,  Q,  is 
set  in  the  groove.  I.    The  card  is  held  on  the  board 'between  clamps,  C  and  A.    The 


tracing  point,  O,  is  set  at  point,  D,  and  the  arm  moved  clockwise,  the  vernier  and 
drum  having  been  set  at  zero. 

Average  Figures  for  Speed  — A  fair  average  figure  may  be 
substituted  in  the  formula  given  above  for  indicated  horse-power, 
when  the  revolutions  per  minute  are  not  known.  It  may  be  found 
as  follows :  Since  the  piston  speed  of  most  motor  carriage  en- 
gines running  at  full  power  is  somewhere  between  400  and  600 


238  SELF-PROPELLED    VEHICLES. 

feet  per  minute,  we  may  take  the  average  of  500  feet,  multiply  it 
by  12  to  reduce  to  inches  and  divide  by  twice  the  length  of  the 
stroke  in  inches.  Thus: 

6,000 
-  =  R.  P.  M. 


Twice  the  stroke  is  used  because  that  expresses  the  space 
covered  by  the  piston  in  each  revolution  of  the  fly-wheel.  Sub- 
stituting this  formula  in  the  typical  engine  mentioned  above,  we 
find  that  : 

6,000 

—=666  revolutions  per  minute, 
9 

which  is  very  nearly  the  correct  figure. 

Roberts  gives  a  more  complicated  formula,  as  follows  : 

."The  following  formula  representing  average  practice  among 

manufacturers  will  be  found  valuable  in  making  the  first  ap- 

proximate calculation  : 

"  Let  H=the  D.  H.  P.  of  the  engine; 
Let  R=the  revolutions  per  minute; 
Then  for  a  four-cycle  engine 
380 

"  (H)  -21 

"In  order  to  solve  the  above  equation  it  is  necessary  to  use 
logarithms.  Suppose  it  is  desired  to  find  the  speed  of  a  15  H.  P. 
four-cycle  engine.  Take  a  table  of  logarithms  and  find  first  the 
logarithm  of  15,  which  is  1.176091  ;  multiplying  by  .21  the  result 
is  .24697911,  which  is  the  logarithm  of  15  to  the  .21  power.  The 
logarithm  of  380  is  2.579784;  substracting  the  logarithm  of 
(IS)21  from  this,  we  have  2.332705,  which  is  the  logarithm  of  215.1. 
The  proper  speed  for  this  engine  is  215  r.  p.  m.  or  thereabout." 

Estimating  Power  Without  Diagrams.  —  The  formulae  given 
above  depend  for  exact  results  on  the  measurement  of  indicator 
diagrams.  But  it  is  possible  to  compute  roughly  without  these. 
An  authority  quoted  previously  gives  the  following  : 

"When  an  estimate  of  an  engine's  capacity  is  desired,  and  no 


ESTIMATING  HORSE-POWER.  239 


diagrams  are  obtainable,  the  approximate  horse  power  attain- 
able in  the  cylinder  may  be  found  by  means  of  the  formula : 

ExVC     ^P"-PExKE         PC-P'xRCx 

XI )  =  H.  P. 

1,000        V  120  140         J 


"No  doubt  the  formula  will  seem  rather  complicated  at  first 
glance,  but  its  application  is  by  no  means  difficult.  Stated  as  a 
rule  it  reads  as  follows  : 

"Multiply  the  exhaust  pressure  by  the  expansion  ratio,  and  sub- 
tract the  product  from  the  explosion  pressure;  divide  what  is  left 
by  1  20,  and  call  the  result  the  'first  quotient.' 

"Multiply  the  initial  pressure  (about  13.2)  by  the  compression 
ratio,  and  subtract  the  product  from  the  compression  pressure;  di- 
vide what  is  left  by  140,  and  call  the  result  the  'second  quotient.' 

"Subtract  the  second  quotient  from  the  first  quotient,  and  multi- 
ply the  remainder  by  the  number  of  explosions  per  minute  and  by 
the  clearance  volume;  divide  this  result  by  1,000." 

By  attentively  reading  this  rule  the  quantities  may  be  readily 
recognized  on  the  formula  where  they  are  designated  by  their 
initial  letters. 

The  same  authority  gives  another  formula  based  on  average 
figures  as  follows  :  Take  the  figure  for  the  difference  between  the 
exhaust  pressure  and  the  initial  pressure  (13.2).  Multiply  it  by  a 
figure  representing  the  average  found  by  adding  the  compression 
ratio  and  expansion  ratio  and  dividing  by  2.  Subtract  the  product 
thus  found  from  the  figure  for  pressure  rise,  which  is  to  say  the 
difference  between  the  pressure  of  explosion  and  the  pressure  of 
compression.  Divide  the  remainder  by  10.  Multiply  the  quotient  thus 
found  by  the  product  of  the  number  of  explosions  per  minute  and 
the  clearance  volume,  and  divide  the  product  by  10,000. 

Expressed  graphically  this  gives  us  : 


ExVC     (P«-PC)-(PE-P' 

__  y  ____  __     =     H.      P. 

10,000  10 

Estimating  the  Power  by  Prony  Brake.  —  The  most  satis- 
factory method  of  testing  the  effective  power  of  an  engine  is  by 
the  use  of  Prony's  brake,  one  form  of  which  is  shown  herewith. 


240  SELF-PROPELLED    VEHICLES. 

Briefly,  it  consists  of  a  band  of  rope  or  strip  iron — the  latter  is 
the  arrangement  shown — to  which  are  fastened  a  number  of 
wooden  blocks,  several  carrying  shoulders  to  prevent  the  con- 
trivance from  slipping  off  the  wheel  rim.  Being  applied  to  the 
circumference  of  the  fly-wheel  the  brake  band  is  drawn  tight,  as 
shown,  so  that  the  blocks  press  against  the  surface  all  around. 
The  brake,  thus  formed,  is  prevented  from  revolving  with  the 
fly-wheel,  by  two  arms,  attached  near  the  top  and  bottom  centres 
of  the  wheel,  and  joined  at  the  opposite  ends  to  form  a  lever, 
which  bears  upon  an  ordinary  platform  scale,  a  suitable  leg  or 
block  being  arranged  to  keep  its  end  opposite  to  the  centre  of 
the  shaft.  By  this  arrangement  the  amount  of  friction  between 
the  brake  band  and  the  revolving  wheel  is  weighed  upon  the 
scales.  For  since  the  brake  fits  tightly  enough  to  be  carried 
around  by  the  wheel,  but  for  the  arms  bearing  upon  the  scale, 
the  amount  of  frictional  power  exerted  by  the  wheel  in  turning 
free  within  the  blocks  may  be  transmitted  and  measured,  just  as 
would  be  the  case  were  a  machinery  load  attached,  instead  of  a 
friction  brake. 

The  Factors  in  the  Formulas. — Accordingly,  the  factors  in 
estimating  the  power  developed  are:  (i)  The  circumference  of 
the  wheel ;  (2)  the  length  of  the  leverage,  measured  on  the  line 
drawn  from  the  centre  of  the  rotating  shaft  to  the  centre  of  the 
scale  platform ;  (3)  the  number  of  revolutions  per  minute ;  (4)  the 
weight  in  pounds  registered  by  the  scales,  less  the  static  weight 
of  the  brake  lever  arms  and  block  resting  on  the  platform.  With 
this  form  of  Prony  brake  the  formula  for  delivered  horse-power 
is  as  follows : 

WxNxLxC 
=B.  H.  P. 

33,000 

in  which  W  is  the  net  weight  as  shown  by  the  scale;  N,  the 
number  of  revolutions  per  minute ;  L,  the  length  of  the  leverage ; 
C,  the  circumference  of  the  braked  fly-wheel.  Their  product 
gives  the  number  of  foot-pounds  developed ;  the  quotient  of  the 
indicated  division  by  33,000  gives  the  efficient  horse-power.  If, 
therefore,  a  given  engine  has  a  fly-wheel  of  16  inches  diameter, 
revolving  at  600  revolutions  per  minute,  and  giving  27.5  pounds 


ESTIMATING  HORSE-POWER.  241 

at  the  scale,  with  a  leverage  of  5  feet,  we  have,  according  to  the 
above  formula  : 

_  346830.57 

=  10.51  horse  power. 


33,000  33,000 

The  diameter,  16  inches,  being  multiplied  by  3.14159,  the  ex- 
pression for  the  ratio  between  the  circumference  and  diameter  of 
a  circle,  gives  50.2655  inches,  which,  divided  by  12,  gives  4.189 
feet  approximately. 

Other  Forms  of  Prony  Brake.  —  In  some  forms  of  Prony 
brake  the  block-bearing  rope  or  band,  instead  of  being  secured 
as  shown  in  the  cut  is  attached  to  the  floor  and  ceiling  —  two 
dynamometers  or  spring  balances  being  interposed.  Thus  in  the 
formula  for  estimating  with  this  form,  the  item  of  leverage 
length  is  omitted,  the  expression  being  : 

WxNxC 

—  -=D.  H.  P. 

33,000 

As  may  be  readily  understood  the  scale  weight  in  this  case 
would  equal  the  product  of  the  weight  and  leverage  length  with 
the  other  formula. 


FIG.  165.— Common  Form  of  Prony  Brake,  for  testing  the  D.  H.  P.  of  an  engine.  An  iron 
band  shod  with  wooden  blocks  is  drawn  tightly  around  the  circumference  of  the  fly- 
wheel. To  this  two  arms  are  attached,  the  other  ends  of  which  bear  upon  the  scale 
platform,  as  shown.  It  is  necessary  that  the  scale  platform  be  raised  to  the  same 
height  as  the  centre  of  the  fly-wheel  shaft.  The  length  of  leverage  is  indicated  as 
5  feet  3  inches,  the  diameter  of  the  wheel  being  3  feet.  These  two  factors,  the 
R.  P.  M.  and  the  recorded  weight,  are  the  essential  elements  in  the  determination  of 
power  as  by  the  above  formula. 


CHAPTER    TWENTY. 


ON   CARBURETTERS   AND   VAPORIZERS. 

Carbu retting  Devices  of  Various  Descriptions. — In  opera- 
ting a  gasoline  vehicle  motor,  it  is  essential  that  the  liquid  fuel 
be  transformed  into  a  gas,  so  as  to  be  fed  to  the  cylinders  with  a 
suitable  mixture  of  atmospheric  air.  This  process  is  performed 
by  a  device  known  as  a  carburetter,  which  consists  in  general  of 
a  vessel  into  which  a  small  amount  of  liquid  gasoline  is  admitted 
as  required,  and  being  there  vaporized  by  air,  which  is  passed 
through  it  or  over  it,  and  by  the  suction  of  the  piston  causes 
the  gasoline  to  rise  through  a  small  orifice  and  mix  with  the 
passing  air  current  in  the  form  of  spray.  There  are  two  com- 
mon forms  of  carburetter;  the  surface  carburetter,  in  which  a 
current  of  air  passing  over  the  surface  of  the  liquid  gasoline,  ab- 
sorbs a  certain  portion  of  it,  and  the  float  feed  carburetter,  or 
sprayer,  in  which  a  current  of  air  is  drawn  by  the  suction  of  the 
piston  stroke,  causing  a  spray  to  rise  from  the  gasoline  through  a 
nozzle,  the  level  of  the  liquid  being  continually  maintained  by  a 
float  controlling  a  needle  valve  to  the  supply  tank.  A  third  form, 
the  filtering  carburetter,  has  several  points  of  resemblance  to  the 
simple  mechanism  sometimes  employed  for  vaporizing  gasoline 
for  the  purpose  of  illuminating  houses.  The  gasoline  is  con- 
tained in  a  suitable  receptacle,  which  stands  in  a  cistern  filled 
with  water  to  a  certain  level ;  a  cylindrical  cover,  balanced  by  a 
weight  passing  over  a  pulley,  is  suspended  in  the  cistern  over  the 
gasoline  receptacle,  and  is  caused  to  rise  by  the  pressure  of  air 
that  has  been  pumped  through  the  liquid  gasoline  and  has  ab- 
sorbed a  sufficient  portion  of  it  to  render  the  mixture  of  air  and 
gas  inflammable.  This  mixture  is  then  fed  to  the  pipes  leading 
to  the  gas  burners  in  the  house. 

Air  thus  charged  with  the  vapor  of  gasoline,  or  other  volatile 
spirit,  is  said  to  be  carburetted.  In  the  practical  construction  of 
carburetters  for  gasoline  vehicle  use,  a  number  of  points  must 
be  considered,  since  in  the  use  of  such  a  devjce  of  any  pattern, 
the  elements  of  jar  and  vibration  likely  to  disturb  the  operation 

242 


CARBURETTERS  AND   VAPORIZERS. 


243 


of  the  instrument,  must  be  provided  against.  Also,  for  numer- 
ous other  reasons,  only  a  portion  of  the  total  fuel  carried  is 
acted  upon  by  the  air  current  at  one  time  in  the  carburetters. 


Fit*.  168.— The  Daimler  Surface  Carburetter,  used  on  the  early  Daimler  cycles  and  car- 
riages. 

Daimler's  Surface  Carburetter.— The  idea  of  using  liquid  fuel 
for  a  gas  engine,  and  carburetting  it  by  a  suitable  instrument, 
was  one  of  the  improvements  introduced  by  Gottlieb  Daimler. 


244  SELF-PROPELLED    VEHICLES. 

Daimler's  carburetter,  a  section  of  which  is  shown  in  an  accom- 
panying illustration,  was  used  on  the  earliest  motor  vehicles,  tri- 
cycles and  carriages  made  by  him.  It  was  a  very  efficient  in- 
strument in  its  day,  but  represents  a  style  of  construction  that 
has  been  entirely  superseded.  It  consisted  of  an  elongated  cylin- 
drical vessel,  which  was  partially  filled  with  gasoline.  Upon  this 
liquid  was  a  hollow  cylindrical  float,  the  shell  of  which  was 
slightly  depressed  upon  the  upper  face,  so  that  the  gasoline  rising 
through  the  hollow  in  the  centre  could  be  readily  exposed  to 
the  action  of  the  air,  drawn  through  the  vessel  by  the  suction  of 
the  piston.  The  float  also  carried  a  vertical  tube,  which  reached 
upward  through  the  top  of  the  inclosed  cylindrical  vessel,  slid- 
ing freely  in  a  second  tube  of  larger  diameter,  in  order  that  the 
float  might  rise  or  fall  to  the  level  of  the  gasoline.  In  the  top 
of  the  cylindrical  vessel  was  also  set  a  cylinder  of  somewhat 
smaller  diameter,  having  a  perforation  in  its  top  admitting  at- 
mospheric air,  and  having  its  base  connected  with  the  interior 
of  the  main  cylindrical  vessel.  These  openings  at  both  top  and 
bottom  could  be  regulated  by  rotary  valves.  At  the  left-hand 
upper  side  of  this  cylinder  was  a  vent,  which  was  connected  with 
the  combustion  chamber  of  the  cylinder.  The  operation  was  as 
follows :  When  the  piston  began  the  suction  stroke,  air  was 
drawn  through  this  vent,  some  of  it  coming  through  the  upper 
openings  already  mentioned,  and  another  portion  through  the 
vents  at  the  base,  which  connected  it  with  the  main  body  of  the 
instrument.  The  air  from  within  this  main  cylinder  was  drawn 
downward  to  the  operating  tube;  the  greater  portion  of  it,  as 
may  be  understood  from  the  figure,  passing  through  the  small 
holes  in  the  base  of  the  tube,  thus  upward  through  the  gasoline 
contained  within  the  central  depression  of  the  body  of  the  float, 
causing  vaporization  and  thoroughly  charging  the  air  drawn  into 
the  cylinder.  As  may  be  seen  from  the  illustration,  the  upper 
cylinder,  which  is  in  connection  with  the  combustion  space,  has  its 
vents  covered  with  wire  gauze ;  the  object  of  this  was  to  prevent 
the  ignition  of  the  contained  gasoline  and  vapor,  in  case  of  back- 
firing in  the  cylinder. 

Maybach's  Float  Carburetter. — On  later  vehicles  made  by 
Daimler  were  used  the  balanced  float  feed  carburetters  invented 
by  his  collaborator,  William  Maybach.  As  first  constructed  by 


CARBURETTERS  AND   VAPORIZERS. 


245 


him,  this  style  of  instrument  was  the  simple  device  shown  in  the 
accompanying  cut.  The  float,  A,  contained  within  a  small  vessel 
connected  by  a  tube,  B,  with  the  valve  chamber  of  the  cylinders, 
F,  bears  upon  its  upper  face  the  spindle  of  a  needle  valve,  which 
regulates  the  rate  at  which  the  gasoline  is  admitted  to  the  car- 
buretter through  the  tube  shown  at  its  top.  This  is  the  simplest 
form  of  the  float  feed  carburetter.  The  action  is  as  follows : 
When  the  piston  in  the  cylinder,  F,  is  making  its  suction  stroke, 
the  valve,  D,  is  opened  inwardly,  compressing  the  spring,  E, 
carried  on  its  stem,  and  giving  admission  to  atmospheric  air,  as 
indicated  by  the  arrows.  Since,  however,  the  end  of  the  tube,  B, 
which  is  reduced  to  form  the  spraying  nozzle,  occupies  the  greater 
part  of  the  air  inlet,  the  strong  spray  of  liquid  gasoline  is  drawn 


FIG.  1R7.— Maybach's  Original  Float  Feed  Carburetter.  A  is  the  hollow  float  carrying 
the  spindle  of  the  needle  valve  at  its  top;  B,  the  tube  leading  into  the  inlet  valve 
space;  C,  the  spraying  nozzle;  D,  the  inlet  valve;  E,  the  inlet  valve  spring;  F,  the 
cylinder  space. 

up  by  suction  and  mixes  with  the  atmospheric  air  in  the  valve 
chamber,  C,  the  proportions  of  the  mixture  being  determined  by 
the  dimensions  of  the  apertures  admitting  additional  air  into  the 
cylinders.  The  defects  of  this  instrument  are  obvious ;  for  since 
the  float.  A,  is  not  balanced  in  any  manner,  its  action  was  liable 
to  be  uncertain  through  the  vibrations  of  travel,  with  the  result 
that  its  regulation  of  the  level  in  the  float  chamber  would  be  un- 
certain if  the  valve  stem  were  not  wrenched  or  broken  so  as  to 
render  the  machine  useless.  Largely  from  the  considerations 
just  noted,  later  types  of  the  float  feed  carburetter  have  been  con- 
structed with  a  very  elaborate  and  reliable  adjustment  to  secure 
the  maintenance  of  the  desired  level  and  the  certain  action  of  the 


246 


SELF-PROPELLED   VEHICLES. 


needle  valve.  The  method  of  admitting  air  to  mix  with  the  gaso- 
line spray  under  suction  of  the  piston  has  also  been  so  improved 
as  to  permit  of  considerable  adjustment  of  the  proportions  in  the 
fuel  mixture. 


FIG.  168.— The  Longuemare  Float  Feed  Carburetter.  A  is  the  float;  B,  B,  the  weighted 
levers  controlling  the  needle  valve;  C,  the  weight  holding  the  needle  valve  closed 
while  the  lever  is  right  in  the  float  chamber;  1),  the  spindle  of  the  needle  valve;  E, 
air  inlet;  F,  pipe  communicating  to  combustion  space  of  cylinder;  G,  cock  for 
admitting  additional  air  supply. 

The  Longuemare  Float  Feed  Carburetter. — The  Longue- 
mare carburetter,  shown  in  an  accompanying  illustration,  is  one 
of  the  most  elaborate  variations  of  the  Daimler-Maybach  type. 


CARBURETTERS  AND   VAPORIZERS. 

The  carburetter  chamber  contains  the  float,  A,  through  which 
passes  the  stem  of  the  needle  valve,  D;  this  needle  valve,  how-^ 
ever,  is  not  attached  to  the  float  as  in  the  earlier  model,  but  is 
normally  held  in  place  by  the  weight,  C,  which  holds  the  port 
leading  to  the  gasoline  tank  normally  closed.  On  either  side  of 
the  weight,  C,  is  fixed  a  small  lever  in  such  a  fashion  that  when 
the  liquid  gasoline  is  at  the  required  level  and  the  float  in  the 
raised  position,  they  are  also  held  up  by  the  weight,  C,  bearing 
upon  their  inner  arms.  When,  however,  the  level  falls,  the.float, 
A,  bears  upon  the  pivoted  weighted  arms,  B  and  B,  at  the  oppo- 
site extremities,  pressing  them  downward,  as  shown  in  the  il- 
lustration, and  causing  the  weight,  C,  carrying  the  valve,  D,  to 
be  raised  upward,  thus  opening  the  inlet  for  the  liquid  gasoline 
until  the  normal  level  is  once  more  restored.  The  mixing  cham- 
ber shown  in  connection  with  this  type  of  carburetter  is  consider- 
ably more  elaborate  than  the  one  used  with  the  Maybach  just 
described.  The  tube,  F,  leads  to  the  combustion  chamber  of  the 
cylinder,  and  when  the  piston  is  making  its  suction  stroke  atmos- 
pheric air  is  drawn  through  the  tube,  E,  passing  around  the  ad- 
justable valve-shaped  nozzle  leading  from  the  float  chamber. 
This  valve-shaped  nozzle  is  of  interesting  construction,  consisting 
of  a  head  having  the  general  form  of  a  mushroom-valve,  to  the 
base  of  which  is  a  threaded  stem,  permitting  of  adjustment  in  the 
size  of  the  orifice,  through  which  the  gasoline  spray  is  drawn  by 
the  suction  of  the  piston.  Directly  above  this  valve-nozzle  are 
fixed  several  layers  of  wire-gauze,  through  which  the  carburetted 
air  passes  on  its  way  to  the  vent,  F.  At  the  point,  F,  as  shown, 
there  are  several  other  layers  of  wire-gauze.  Their  object  is 
principally  to  prevent  all  danger  of  explosion,  or  of  disablement, 
to  the  instrument  in  the  event  of  burning-back,  which  is  liable  to 
take  place  if  the  inlet  valves  are  not  arranged  to  close  promptly, 
or  if  they  should  be  in  any  other  fashion  disabled.  The  quantity 
of  air  admitted  to  the  carburetter  through  the  inlet  port,  E,  is 
controlled  by  a  cylindrical  valve  having  the  same  general  con- 
struction as  an  ordinary  faucet,  the  opening  of  which  is  con- 
trolled by  the  upright  arm  shown  just  lelow  the  cock,  G.  A  still 
further  adjustment  of  the  mixture,  particularly  when  a  larger 
portion  of  air  is  desired,  may  be  obtained  by  opening  this  cock, 
G,  and  admitting  the  air  from  above.  In  spite  of  its  complica- 
tion, this  instrument  has  been  very  widely  used, 


248 


SELF-PROPELLED    VEHICLES. 


The  Peugeot  Carburetter. — The  float  feed  carburetter  used 
on  the  Peugeot  carriages,  although  simpler  in  its  general  details, 
has  many  of  the  excellent  features  of  the  instrument  just  de- 
scribed. In  this  also,  the  needle  valve  is  held  on  a  rod  which 
passes  through  the  body  of  the  float,  being  also  held  in  a  de- 
pressed position,  so  as  to  close  the  vent  by  a  weight,  which  is 
raised  by  pairs  of  pivoted  levers  under  the  weight  of  the  float 
whenever  the  level  sinks  below  the  required  point.  The  mixing 
tube  is  connected  at  the  base  with  the  combustion  chamber  of  the 
cylinder,  admitting  air  through  the  tube  coming  in  vertical  direc- 


ATO  INLET. 


ADJUSTABLE  AIR   VALVE. 


TO  CYLINDER. 


TALVK  FOR  EXTRA  AIR. 


FIG.  169.— TheTPeugeot  Carburetter.  This  has  many  points  in  common  with  other  car- 
buretters, except  that  the  valve  levers  are  differently  arranged;  the  spraying  nozzle 
at  the  side  of  the  mixing  tube,  and  the  air-inlet  from  above. 


tion  from  above,  the  spray  being  drawn  through  the  nozzle, 
which  is  shaded  in  black.  This  nozzle  is  of  the  ordinary  pattern 
with  a  reduced  mouthpiece.  Directly  above  it  is  an  adjustable 
sliding  valve,  controlled  by  a  turn-screw  in  the  wall  of  the  cham- 
ber, which  varies  the  quantity  of  air  admitted,  and  hence  also  the 
richness  of  the  mixture.  Additional  air  may  also  be  admitted 
when  desired,  through  the  tube  leading  from  the  base  of  the 
mixing  chamber,  controlled  by  the  cock  as  shown. 


CARBURETTERS  AND    VAPORIZERS. 


249 


The  Perfected  Daimler  Carburetter. — The  float  feed  carbu- 
retters used  on  the  later  patterns  of  the  Cannstadt-Daimler  car- 
riages, and  also  on  those  manufactured  in  France  by  the  firm  of 
Panhard-Levassor,  are  in  several  respects  similar  to  the  one  last 
described.  In  these  carburetters  the  spindle  of  the  needle-valve 
is  passed  through  the  tube  in  the  centre  of  the  float.  From  the 
top  of  the  gasoline  chamber  hang  two  small  supports,  into  which 
are  pivoted  levers  working  in  a  collar  on  the  valve  rod  at  one 
extremity  of  each,  and  having  weights  bearing  upon  the  top  of 
the  float  at  the  other.  The  top  of  the  spindle  pro- 


Fio.  170.— The  "Phenix"  Daimler  Carburetter.     A  is  the  gasoline  needle  valve;  B,  the 
weighted  controlling  levers;  C,  the  float;  D,  the  float  chamber;  E,  the  gasoline  sup- 

Kly  tube;  F,  the  spraying  nozzle;  G,  the  "  mushroom  "  spray  deflector;  H,  the  port 
jading  to  the  cylinder  chamber;   I,  the  air  inlet.     The  air  entering  the  mixing 
chamber  follows  the  course  of  the  arrows. 

trudes  through  the  cover  of  the  float  chamber  and  is 
normally  held  in  a  depressed  position  by  a  spring  bear- 
ing upon  its  end,  thus  ensuring  the  closure  of  the 
needle-valve  and  the  stoppage  of  the  gasoline  feed  so  long 
as  the  desired  level  is  maintained ;  as  soon,  however,  as  this  level 
falls,  the  weighted  extremities  of  the  two  levers  are  depressed, 
causing  the  opposite  ends  to  bear  upon  the  collar  on  the  valve 
spindle,  thus  forcing  it  up  and  opening  the  valve.  In  the  lettered 
section  of  this  carburetter,  we  may  see  the  needle-valve  at  A,  be- 


250 


SELF-PROPELLED   VEHICLES. 


low  it  being  shown  the  supply  pipe  leading  from  the  gasoline 
tank,  and  the  layer  of  wire-gauze  interposed  just  below  the  en- 
trance to  the  float  chamber.  The  simple  weighted  levers  are 
shown  at  By  the  hollow  float  at  C,  the  passage  for  the  admission 
of  air  at  /,  and  the  passage  leading  to  the  combustion  chamber 
at  H.  The  operation  is  precisely  similar  to  that  of  the  other  car- 
buretters already  described.  Directly  above  the  spring  nozzle 
is  fixed  a  cone,  or  deflector,  G,  which  serves  to  disperse  the  spray 
which  is  forced  against  it  by  air  pressure,  thus  securing,  as  as- 
serted, the  more  complete  and  uniform  mixture  of  air  and  gaso- 
line vapor. 


FIG.  171.— The  Duryea  Float  Feed  Carburetter  or  Sprayer. 

The  Duryea  Float  Carburetter  — A  large  proportion  of  gaso- 
line carriages  manufactured  in  America  have,  up  to  the  present 
time,  been  equipped  with  float  carburetters  of  the  same  general 
construction  as  those  already  described.  Very  exaggerated 
claims  are  made  by  several  manufacturers  as  to  the  superiority 
of  their  own  contrivances,  but  the  principal  innovation  which 
they  can  sho\v  seems  to  consist  in  improved  devices  for  securing 
undisturbed  action  of  the  needle-valve,  and  for  regulating  the 
proportions  of  the  fuel  mixture  fed  to  the  cylinder.  The  Duryea 

carburetter,  or  sprayer,  shown  in  an  accompanying  cut,  is  per- 


CARBURETTERS  AND    VAPORIZERS. 


251 


haps  one  of  the  simplest  among  those  produced  in  America.  Like 
the  float  feed  carburetters  already  described,  it  has  a  gasoline 
chamber  in  which  is  placed  a  hollow  cylindrical  float ;  this  float, 
like  that  used  in  the  earliest  form  of  the  Maybach  carburetters, 
carries  the  point  of  the  needle-valve  secured  to  its  top,  thereby 
closing  the  entrance  of  the  gasoline  from  the  tank  through  the 
top  of  the  float  chamber,  so  long  as  the  proper  level  is  maintained 
within.  Unlike  the  early  Maybach  carburetter,  however,  this 


FIG.  172  —The  De  Dion  &  Bouton  Vaporizer.  A  is  the  cover  of  the  air  chamber;  B,  the 
air  valve;  C,  the  float:  D,  the  mixing  chamber;  E,  gasoline  supply;  F,  gasoline 
needle  valve;  G,  valve  controlling  lever.  Arrow  (1)  indicates  course  of  uir  through 
mixing  chamber;  arrow  (2),  course  of  additional  air  through  valve  B. 

float  is  balanced  by  vertical  guides  at  four  points  on  its  circum- 
ference, as  may  be  readily  understood  from  the  plan  and  sec- 
tional views  given  herewith.  Connected  with  the  float  chamber 
is  a  vertical  passage,  whose  height  may  be  controlled  by  an  ad- 
justing screw,  shown  in  the  figure,  and  which  connects  to  a 
spraying  nozzle,  extending  into  the  tube  or  passage  from  atmos- 
phere to  the  combustion  chamber  of  the  cylinder.  As  shown  in 
the  plan  view,  the  spraying  nozzle  i$  bent  around  to  a  right  angle 


252  SELF-PROPELLED    VEHICLES. 

at  the  end  and  is  enclosed  in  a  short  length  of  small  diameter 
tubing.  The  inflow  of  air  through  the  larger  tube  is  controlled 
by  an  adjustable  rotary  valve.  The  liquid  gasoline  is  fed  to  the 
float  chamber  from  the  supply  tank  through  a  length  of  tubing 
encased  in  a  cylindrical  cover  of  wire-gauze,  intended  primarily 
to  prevent  the  passage  of  any  impurities  which  might  interfere 
with  the  action  of  the  needle  valve  or  clog  the  small  passages 
leading  to  the  spraying  nozzle. 

The  De  Dion  Float  Carburetter. — The  float  feed  carburetter, 
used  on  the  later  models  of  the  De  Dion  &  Bouton  gasoline  car- 
riages, combines  several  features  in  radical  departure  from  the 
patterns  of  carburetter  already  noticed.  As  shown  in  the  accom- 
panying sectional  plan  and  elevations,  it  consists  of  a  cylindrical 
chamber,  H,  within  which  is  contained  a  float,  C.  This  float  differs 
from  the  kind  used  on  other  carburetters  in  the  fact  that  it  is  con- 
structed out  of  two  annular  cylindrical  shells,  united  by  flanged 
and  soldered  ring  heads.  Its  shape,  with  the  hollow  space  in 
the  centre,  makes  possible  the  construction  allowing  the  mixing 
chamber  to  be  set  in  the  centre  of  the  float  chamber,  the  float  sur- 
rounding it  and  sliding  against  its  cylindrical  walls.  The  supply 
of  gasoline  is  admitted  to  the  float  chamber  through  the  adjust- 
able valve  shown  at  F,  the  opening  and  flow  being  controlled  by 
the  lever,  G,  which,  as  shown,  is  in  a  raised  position,  thus  allow- 
ing the  needle-valve  to  be  closed,  so  long  as  the  weight  of  the 
float  does  not  bear  upon  it.  The  spraying  nozzle  is  located  in 
the  mixing  chamber,  which,  as  already  stated,  is  entirely  sur- 
rounded by  the  ring-shaped  float.  The  gasoline  is  drawn  by  suc- 
tion through  this  nozzle  by  the  air  entering  the  tube,  /,  and  fol- 
lowing the  direction  indicated  by  the  arrow,  marked  i  (one)  in 
the  plan  and  right-hand  sectional  elevation.  As  shown  in  the 
plan,  there  is  also  a  cylindrical  valve,  B,  which  may  be  rotated  by 
the  lever,  7,  attached  to  the  stem  passing  through  the  cover,  K, 
of  the  upper  chamber,  A.  By  this  handle  the  charge  may  be 
throttled  within  the  desired  limits  by  regulating  the  inflow  of  ad- 
ditional air  through  the  tube,  t,  as  indicated  by  the  arrow,  marked 
2  (two)  in  the  plan.  This  carburetter  has  the  advantage  of  com- 
pactness and  simplicity  of  construction.  Another  form  of  float 
feed  carburetter  used  on  De  Dion  carriages  is  shown  in  Fig. 
282.  It  assimilates  the  common  patterns, 


CARBURETTERS  AND   VAPORIZERS. 


253 


The  Huzelstein  Valve  Carburetter. — From  the  earliest  days 
of  the  use  of  liquid  fuels  for  explosive  engines,  numerous  in- 
ventors have  produced  designs  of  carburetters  or  vaporizers  that 
operate  without  the  complications  of  a  float  chamber  and  needle- 
valve,  whose  opening  is  regulated  by  the  level  of  the  gasoline 
contained  therein.  One  of  the  most  typical  devices  of  this  de- 


Fio  173.— The  Huzelstein  Carburetter.  A  is  the  inlet  for  gasoline;  B,  the  valve  control- 
ling inlet;  C,  the  tube  leading  to  cylinder  combustion  space;  D,  tube  for  leading  hot 
exhaust  gases  around  the  jacket  on  the  mixing  chamber.  Arrows  indicate  entrance 
for  air  and  course  of  mixture  to  cylinder. 

scription  is  the  Huzelstein,  or  "Universal,"  carburetter,  shown  in 
an  accompanying  illustration.  It  consists  of  a  vertical  cylindrical 
chamber,  within  which  is  a  valve  controlled  by  a  helical  spring 
and  hung  on  a  spindle,  the  upper  end  of  which  forms  a  needle- 
valve,  closing  the  inlet  port  for  liquid  gasoline,  shown  at  the  top 
of  the  cylindrical  chamber.  The  gasoline  from  the  supply  tank 


254 


SELF-PROPELLED   VEHICLES. 


is  fed  through  a  tube,  A,  leading  to  this  chamber  and  having  its 
rate  of  supply  regulated  by  a  needle-valve  carried  at  the  end  of 
an  adjustable  screw  shank,  upon  the  upper  end  of  which  is  the 
handle,  B.  Connection  with  the  interior  of  the  main 'cylindrical 
chamber  and  the  combustion  space  of  the  cylinder  is  had  by  the 
tube,  C.  The  tube,  D,  is  also  connected  with  the  combustion 
space  so  as  to  permit  the  heated  products  of  combustion  to  cir- 
culate through  the  jacket  or  passage  around  the  upper  part  of  the 
mixing  chamber  above  the  valve.  The  suction  of  the  piston 
operates  to  open  the  valve,  drawing  it  from  its  seat  and  depress- 
ing the  helical  spring  around  the  lower  portion  of  the  valve  spin- 


JBUIIIWpffiBiffl  L 

^^^K^^ 


FIG.  174.—  The  James  Valve.  B,  fuel  inlet  valve;  C.  spring  controlling  B;  D  is  the  scale 
dial  showing  proportions  of  air  and  gasoline;  E,  the  wheel  controlling  gasoline  valve; 
F,  clip  or  top  for  holding  E  in  position;  G,  gasoline  supply  tube;  H,  air  inlet;  I.  en- 
trance to  cylinder;  J,  entrance  for  gasoline;  K,  cover  of  valve  chamber;  L,  wheel 
and  spindle  controlling  tension  of  spring,  C. 

die.  This  process,  of  course,  opens  the  needle  valve  leading  from 
the  gasoline  feed  pipe  and  permits  the  inflow  of  a  small  quantity 
of  liquid  gasoline.  This  is  mixed  with  the  air  drawn  through  the 
opening  indicated  by  the  arrows  at  the  top  of  the  chamber,  the 
process  of  mixing  being  perfected  by  the  heat  of  the  vapors  pass- 
ing through  the  tube,  D,  and  around  the  chamber  in  connection 
with  it ;  also,  by  the  friction  experienced  in  passing  through  the 
narrow  clearances  between  the  open  valve  and  its  seat.  Between 
the  periodic  suction  strokes  of  the  piston,  the  air  in  the  upper 
portion  of  the  mixing  chamber  above  the  valve  is  made  to  ab- 
sorb some  of  the  heat  circulating  around  it,  and  hence,  according 


CAR&UR2TTERS  ANti   VAPORIZERS.  255 

to  the  theory  of  the  inventor,  is  better  prepared  to  mix  perfectly 
with  the  gasoline  mist.  This  carburetter  has  seen  considerable 
use  in  France  and  some  other  European  countries. 

The  James-Lunkenheimer  Valve. — Several  well-known  makes 
of  American  carburetters  are  constructed  to  operate  along  the 
same  general  lines  as  the  Huzelstein,  and,  like  the  majority  of 
American  improvements  in  motor  vehicle  construction,  have  the 
advantage  of  greater  simplicity,  strength  and  compactness. 
Among  these  we  may  mention  the  James  mixing  valve,  shown 
herewith.  This  device  consists  of  a  globular  valve  chamber  hav- 
ing'three  openings  or  vents,  H,  I  and  /.  As  shown  in  the  sec- 
tional view,  the  opening,  H,  is  closed  by  the  mushroom  valve,  B, 
under  tension  of  the  spring,  C.  The  passage,  /,  is  connected  di- 
rect to  the  combustion  chamber  of  the  cylinder,  and  at  the  suc- 
tion stroke  of  the  piston,  the  air  is  drawn  through  the  tube,  H, 
its  pressure  causing  the  valve,  B,  to  rise  from  its  seat.  The  air 
drawn  through  the  passage,  //,  also  draws  as  spray  a  small  por- 
tion of  liquid  gasoline  through  the  tube,  G,  which  connects 
through  the  passage,  /,  with  the  gasoline  supply  tank ;  thus  se- 
curing a  very  good  fuel  mixture,  according  as  the  play  of  the 
valve,  B,  and  the  opening  of  the  tube,  G,  are  adjusted.  The 
proportionate  amount  of  gasoline  fed  into  the  cylinder  through 
the  passage,  /,  of  the  tube,  G,  is  controlled  by  a  needle-valve  car- 
ried on  the  spindle  at  the  hand-wheel,  E,  the  proportionate  open- 
ing of  the  valve  being  indicated  on  the  graduated  disc,  D,  by  the 
position  of  the  clip,  F.  The  play  of  the  valve  is  also  regulated 
by  the  position  of  the  spindle  carried  on  the  hand-wheel,  L,  which 
is  threaded  so  as  to  be  raised  or  lowered  as  required.  Mixing 
valves  of  this  description  have- been  adopted  on  several  makes  of 
American  gasoline  carriages,  notably  the  Winton,  with  appar- 
ently favorable  results. 

The  Improved  Filtering  Carburetter. — Another  interesting 
carburetting  device,  also  of  American  design,  and  known  as  the 
"Auto  Carburetter,"  is  shown  in  an  accompanying  illustration. 
Here  connection  to  the  gasoline  supply  tank  is  had  by  port,  B, 
leading  into  a  simple  globular  chamber,  through  which 
is  fixed  the  spindle  of  an  adjustable  needle-valve,  con- 
trolling the  entrance  to  the  cylindrical  chamber,  K, 


256 


SELF-PROPELLED    VEHICLES. 


within  which  are  fixed,  at  a  slight  incline,  eight  semi- 
circular pieces  of  wire-gauze.  The  gasoline,  admitted  through 
the  opening  of  the  needle-valve,  drips  upon  these  pieces 
of  gauze,  any  overflow  from  one  falling  to  that  next  below  it,  so 
that  the  air  drawn  through  the  ports,  C,  opening  into  the  top  of 


FIG.  175.— The  "Auto"  Carburetter.  A,  wheel  controlling  needle  valve;  B,  gasoline 
inlet;  C,  C,  air  inlets;  E,  throttle  lever;  G,  pipe  to  cylinder;  H,  drip  cock;  K,  inner 
cylinder  containing  segments  of  wire  gauze;  L,  valve  controlling  air  inlets. 

the  cylinder,  becomes  thoroughly  charged  with  gasoline  mist  be- 
fore reaching  the  bottom,  connection  being  made  with  the  com- 
bustion space  of  the  cylinder  through  the  tube,  G,  which  connects 
direct  with  another  larger  cylinder  placed  outside  of  the  first. 
The  air  is  drawn  through  the  layers  of  gauze  down  through  the 


CARBURETTERS  AND   VAPORIZERS.  257 

inner  cylinder  to  its  bottom,  then  up  and  around  it.  The  open- 
ing of  the  gasoline  inlet  tube,  G,  is  controlled  by  a  cock,  F,  on  the 
rod,  E,  so  that  the  amount  of  mixture  may  be  varied  or  the  tube 
entirely  closed.  The  drain  cock,  H,  is  fixed  at  the  base  of  the 
outer  cylinder,  so  as  to  carry  off  any  leakage  of  gasoline  or  un- 
vaporized  residue  that  might  collect  within  it. 

Supplemental  Mixing  Chambers. — Many  of  the  earlier  types 
of  explosive  motors  for  vehicle  use  were  equipped  with  a  mixing 
chamber  in  addition  to  the  carburetting  device.  This  mixing 
chamber  in  its  typical  construction,  as  used  on  the  Benz  car- 
riages and  some  of  the  Daimlers,  consisted  of  two  tubes  tele- 
scoped together,  the  inner  one  of  which  had  longitudinal  open- 
ings, so  that,  the  further  it  was  pulled  out  from  the  outer  tube, 
the  larger  the  amount  of  air  that  was  admitted  with  the  carburet- 
ted  mixture  under  the  suction  of  the  piston.  To  diminish  the 
air  supply,  the  same  tube  was  pushed  in.  However,  in  later  en- 
gines .of  the  four-cycle  type,  the  practice  of  drawing  in  atmos- 
pheric air,  in  addition  to  that  coming  through  the  carburetter, 
has  been  abandoned,  and  carburetters  are  now  constructed,  as  we 
have  seen,  with  air  and  gasoline  inlet  valves  that  may  be  adjusted 
so  as  to  vary  the  proportions  of  the  mixture  passing  through  the 
instrument.  There  is  thus  but  one  inlet  valve  to  the  cylinder,  and 
that  is  used  solely  for  admitting  the  regulated  fuel  mixture  from 
the  carburetter. 

Troubles  With  Carburetters. — Under  ordinary  circumstances, 
as  in  summer  or  in  dry  weather,  the  process  of  carburetting  the 
liquid  fuel,  so  as  to  form  a  mist  or  vapor,  suitable  for  explosion 
in  the  cylinder,  is  very  readily  perfected  with  mineral  spirit  of 
the  proper  quality.  It  has  been  found,  however,  that  cold  and 
damp  weather  are  apt  to  materially  reduce  the  volatility  of  the 
liquid,  with  the  result  that  the  power  efficiency  of  the  motor  is 
oftentimes  reduced  nearly  one-half.  In  order  to  partially  combat 
this  difficulty,  numerous  motor  carriage  builders,  both  in  Amer- 
ica and  abroad,  have  arranged  to  place  the  carburetting  device  in 
or  near  the  muffler,  so  that  the  heat  of  the  exhausted  residua  of 
combustion  may  act  to  promote  the  carburettization  of  the  fuel 
and,  as  far  as  possible,  neutralize  the  ill  effects  due  to  unfavorable 
weather  or  temperature.  The  device  is  a  desirable  feature  under 


VEHICLES. 


any  circumstances ;  since,  as  has  been  recognized  by  numerous 
inventors,  heat  materially  helps  the  process  of  vaporizing — heated 
air  will  absorb  the  vapor  of  gasoline  much  more  readily  than 
cold  air ;  also  heat  will  ensure  the  best  possible  results,  even  with 
the  use  of  the  poorer  qualities  of  liquid  fuel. 

Kerosene  Vaporizers. — Although  for  numerous  reasons,  such 
as  its  stench,  dirtiness  and  inferior  vaporizing  qualities,  kerosene 
has  been  used  successfully  in  but  few  explosive  engines,  pro- 
pelling motor  carriages,  the  few  employing  it  as  fuel  have  em- 
bodied with  the  vaporizing  device  certain  facilities  for  so  preheat- 


Fig.  176.—  The  Blackstone  Kerosene  Vaporizer.  As  is  evident,  the  oil  sprayed  in  at  the 
right-hand  top  of  the  cylinder  passes  through  an  annular  space  around  the  "chim- 
ney "  of  the  hot  tube,  passing  thence  to  the  space  behind  the  inlet  valve. 

ing  the  liquid  that  the  mist  formed  by  the  injection  of  air,  under 
suction  of  the  engine  piston,  is  rendered  as  rich  as  possible.  This 
provision  is  in  obedience  to  the  quality  of  kerosene,  which  ren- 
ders it  much  more  readily  volatile  when  heated  than  when  cold — 
for,  although  many  qualities  of  this  oil  have  the  "flash  point,"  at 
which  inflammable  vapors  are  given  off,  at  a  very  low  tempera- 
ture, the  process  is  greatly  facilitated  at  higher  temperatures, 
when  also  many  of  the  heavier  constituent  elements  may  be  taken 
up,  as  mist,  by  the  air  passing  through,  or  over,  the  liquid.  . 
A  kerosene  vaporizing  device  is  shown  in  an  accompanying 


CARBURETTERS  AND   VAPORIZERS. 


259 


cut,  which  exhibits  the  construction  to  advantage.  Upon  the 
inlet  valve  chamber  of  the  cylinder,  and  around  the  hot  tube  ig- 
niter opening  into  it,  is  set  a  metal  chimney  having  an  annular 
channel  or  jacket  between  its  walls  and  entirely  around  its  cir- 
cumference. Into  this  jacket  the  oil,  dripping  from  a  small  tube 
into  a  funnel  at  the  upper  right-hand  of  the  figure,  enters  with 
air,  also  drawn  into  the  funnel  by  piston  suction;  both  flowing 
around  through  the  jacket  space,  which  is  heated  by  the  flame 
employed  to  keep  the  hot  tube  incandescent.  The  heat,  acting 
on  the  oil  and  air,  serves  to  break  up  the  former  into  a  mist, 
which  is  carried,  through  the  channel  at  the  left-hand  lower  por- 
tion of  the  annular  jacket,  to  the  chamber  directly  behind  the  in- 
let valve,  as  shown.  At  the  suction  stroke  of  the  piston,  the  oil 
and  air  mist  is  drawn  into  the  cylinder  clearance,  together  with 
additional  air  coming  through  the  tube  shown  at  the  lower  left- 
hand  corner  of  the  figure.  The  proportions  of  the  additional  air 
supply  being  adjusted,  as  desired,  the  explodability  and  power  of 
the  charge  may  be  regulated  to  power  and  speed  requirements. 


• 


FIG.  177.— A  Typical  Float  Feed  Carburetter      This  cut  gives  an  outside  elevation  of 
the  instrument  shown  in  section  in  Fig.  134. 


CHAPTER    TWENTY-ONE. 

ON    THE    SEVERAL    METHODS    OF    FIRING    THE     CHARGE     IN 
A   GAS   ENGINE   CYLINDER. 

Firing  the  Charge  in  Cylinder. — As  already  stated  in  a 
previous  section,  the  fuel  mixture  of  air  and  gas,  after  it  has  been 
drawn  into  the  combustion  chamber  of  the  cylinder,  is  ignited 
explosively,  thus  being  compelled  to  assume  its  maximum  vol- 
ume, by  some  source  of  heat  which  acts  periodically.  As  also 
mentioned,  there  are  several  methods  of  accomplishing  this  re- 
sult; several  of  them  depending  for  operation  upon  the  act  of 
compressing  the  charge. 

Firing  the  Charge  by  Heat  of  Compression. — In  the  Diesel 
four-cycle  engine,  the  explosion  of  the  charge  is  accomplished 
entirely  by  the  temperature  produced  by  the  compression  stroke. 
At  the  suction  stroke  of  the  piston,  pure  atmospheric  air  is  ad- 
mitted to  the  combustion  chamber,  and  at  the  completion  of  the 
compression  stroke,  which  in  this  engine  extends  all  the  way 
to  the  rear  head  of  the  cylinder,  it  is  compressed  to  about  550 
pounds  to  the  square  inch,  which  produces  a  temperature  about 
equal  to  the  heat  of  combustion.  Very  shortly  after  the  begin- 
ning of  the  next  out-stroke  the  fuel  charge,  which  may  be  gaso- 
line vapor,  coal  gas  or  atomized  oil,  is  forced  into  the  combus- 
tion chamber  under  the  still  higher  pressure:  the  result  is  that 
its  temperature,  due  to  compression  in  an  auxiliary  cylinder 
prepared  for  that  purpose,  is  already  sufficient  to  ignite  it  explo- 
sively, and  this  result  follows  immediately  it  comes  into  contact 
with  the  oxygen  of  the  air  contained  within  the  clearance  of  the 
cylinder.  By  the  return  stroke  of  the  piston,  the  burned-out 
gases  are  entirely  swept  from  the  cylinder.  While,  according 
to  authorities,  the  operation  of  the  Diesel  motor  is  very  satis- 
factory in  practice,  the  fact  that  it  requires  an  auxiliary  cylinder 
to  compress  the  fuel  gas  to  a  very  high  degree  effectually  pre- 
cludes its  use  for  purposes  such  as  motor  vehicles,  where  all  the 
available  power  is  desirable  for  locomotion.  It  would  also  be 
quite  impossible  to  operate  it  successfully  without  such  press- 

280 


METHODS  OF  IGNITION. 


261 


ure,  or  with  fuel  mixtures  produced  by  any  other  form  of  car- 
buretting  device  as  above  described. 

Firing  the  Charge  by  Hot  Head. — Another  method  of  ignit- 
ing the  cylinder  charge  by  hot  walls  and  a  temperature  main- 
tained by  the  act  of  compression  is  that  used  in  connection  with 
the  Hornsby-Akroyd  engine,  already  noticed.  In  this  engine, 


FIG.  178.— Diagram  of  the  Hornsby-Akroyd  Ignition  System.  At  the  end  of  the  cylinder 
is  a  box,  or  chamber,  connected  to  it  by  a  narrow  neck.  During  the  suction  stroke," 
shown  in  the  first  figure,  air  is  drawn  into  the  cylinder  and  oil  sprayed  into  the  hot 
igniting  chamber. 

the  rear  end  of  the  cylinder  is  connected  by  a  narrow  passage 
with  the  closed  chamber,  whose  general  construction  has  been 
compared  to  a  bottle  or  jug  with  a  shortened  neck;  into  this 
chamber  also,  at  some  convenient  point,  extends  a  vaporizing 
nozzle  which  is  in  connection  with  the  source  of  liquid  fuel  sup- 
ply. On  starting  the  engine,  the  first  act  is  to  heat  this  hot 
chamber  with  a  suitable  torch,  so  as  to  bring  it  to  the  tempera- 


202 


SELF-PROPELLED    VEHICLES, 


ture  required  for  exploding  the  charge.  On  the  suction  stroke 
of  the  piston,  air  is  drawn  into  the  combustion  chamber  of  the 
cylinder  through  the  ordinary  poppet  valve  opening  direct  to 
atmosphere.  At  the  same  time,  also,  oil  spray  is  forced  through 
the  atomizing  nozzle  directly  into  the  hot  chamber,  where,  al- 
though the  temperature  is  fully  sufficient  to  produce  ignition, 
there  is  an  insufficient  quantity  of  oxygen  to  accomplish  this 
result  prematurely.  The  return  stroke  of  the  piston,  compress- 


I/G.  179.— Boots'  -Kerosene  Oil  Motor  for  Vehicle  Use.  Sectional  view  showing  the  hot 
tube  ignition,  oil.  vapor  and  air  inlet  and  reciprocating  parts.  A  is  the  vaporizing 
chamber  surrounding  the  chimney  of  the  hot  tube,  D.  The  eccentric,  M,  on  the  cam 
shaft  actuates  the  exhaust  valve,  P,  held  in  place  by  the  spring,  L,  at  the  same 
time  moving  the  link,  K,  which  opens  a  valve  contained  in  H,  allowing  a  small 
amount  of  oil  to  be  sprayed  through  the  tubes,  E,  F,  G.  into  the  circulating  chambers 
contained  around  the  hot  tube,  D,  as  shown  at  B.  The  oil  circulating  around  the 
heated  space  is  transformed  into  vapor,  which  is  fed  into  the  channel,  C,  behind  the 
inlet  valve,  O,  which  is  opened  bv  compression  of  its  spring  at  the  suction  stroke. 
The  valve.  R,  controlled  by  an  adjustable  compression  spring,  also  admits  sufficient 
air  into  the  cylinder  to  give  a  mixture  of  the  required  proportion.  The  reciprocating 
parts  are  the  piston,  S,  the  connecting  rod  joined  by  a  strap,  T,  to  the  crank  pin, 
opposite  to  which  is  the  balance  weight,  N.  This  section  very  well  illustrates  tha 
workings  of  the  type  of  explosive  motor  using  hot  tube  ignition. 

ing  the  air  contained  in  the  cylinder  clearance  to  a  very  high 
degree,  forces  a  certain  portion  of  it  through  the  narrow  passage 
connecting  with  the  hot  chamber ;  and  ignition  immediately  be- 
gins, the  burning  gases  expanding  and  rushing  into  the  cyl- 
inder during  the  succeeding  out-stroke  until  the  maximum  vol- 
ume is  reached.  After  the  engine  has  taken  up  its  cycle,  the 
temperature  within  the  hot  chamber  is  constantly  maintained 


METHODS  OF  IGNITION.  263 

by  the  succession  of  explosive  ignitions  at  high  pressure,  in  pre- 
cisely the  same  fashion  as  that  already  described  in  connection 
with  the  Diesel  engine ;  the  external  source  of  heat  being  then, 
of  course,  withdrawn. 

Firing  the  Charge  by  Incandescent  Tube. — The  hot  head 
ignition  system  has  been  used  very  little,  if  at  all,  in  connection 
with  engines  using  mineral  spirits  as  fuel.  It  is  also  a  compara- 
tively recent  device,  the  earliest  gas  engines,  as  constructed  by 
Otto  and  his  collaborators,  having  a  separately  supplied  and  con- 
stantly burning  gas  flame,  which  was  periodically  connected  with 
the  combustion  chamber  of  the  cylinder  by  a  peculiarly  con- 
structed slide-valve,  the  explosion  of  the  charge  being  accom- 
plished by  a  certain  portion  of  the  compressed  mixture  coming 
into  contact  with  the  flame.  As  a  variation  of  and  improvement 
on  the  above-mentioned  device,  the  hot  tube  ignition  was  invented, 
the  essential  features  of  which  are  a  tube  of  metal  and  porcelain, 
one  end  of  which  is  connected  direct  with  the  combustion  cham- 
ber, the  other  being  closed.  Around  and  against  this  tube  the 
flame  of  a  separately  supplied  gas  burner  is  allowed  to  play,  thus 
producing  the  required  temperature  for  explosion.  With  some 
engines  using  hot  tube  ignition,  the  connection  with  the  clyinder 
is  controlled  by  a  slide-valve  in  somewhat  similar  fashion  to  that 
used  on  the  Otto  engine,  the  valve  being  positively  operated,  so 
as  to  open  and  admit  the  compressed  mixture  into  the  hot  tube 
at  the  proper  point  in  the  cycle.  With  others,  there  is  no  valve 
whatever,  the  act  of  compression  alone  operating  to  force  the 
mixture  into  the  tube  and  begin  the  process  of  ignition  at  or 
shortly  before  the  end  of  the  compression,  stroke.  As  may  be 
understood,  however,  such  an  arrangement  is  liable  to  cause  pre- 
mature ignition  under  certain  conditions,  and  is  inferior  to  a 
well-geared  device  for  timing  the  moment  of  ignition.  Accord- 
ingly, a  "timing  valve,"  such  as  is  shown  in  an  accompanying 
figure,  positively  operated  from  the  cam-shaft,  has  been  used 
with  some  gas  engines.  In  this  device,  the  valve,  H,  is  held  open 
throughout  the  firing  and  exhaust  strokes  of  the  piston,  so  that 
it  may  be  swept  clean  of  the  burned-out  gases  contained  within  it. 
Upon  the  completion  of  the  exhaust  stroke  it  is  closed,  and  so  re- 
mains until,  at  the  predetermined  point  in  the  cycle,  the  push  rod 

is  again  actuated  from  the  cam-§haftf 


264 


SELF-PROPELLED    VEHICLES. 


Troubles  with  Hot-Tube  Ignition. — In,  most  gasoline  vehicle 
engines  using  the  hot-tube  ignition,  there  is  no  provision.,  such 
as  a  geared  timing  valve  of  the  general  description  noted  above. 
Consequently,  the  hot  tube  opens  direct  into  the  combustion 
space  of  the  cylinder — being  closed  from  it  at  no  time  in  the 
cycle.  Some  authorities  have  noted  serious  objections  to  the 
hot-tube  ignition  system,  alleging  that,  under  various  conditions, 


FIG.  180.— A  Hot  Tube  Igniter,  with  a  Geared  Timing  Attachment  for  Reg- 
ulating the  Point  of  Firing.  G  is  the  hot  tube  enclosed  with  a  cylin- 
drical case  having  a  perforated  cap,  H,  at  the  top.  The  heat  of  the 
tube  is  maintained  by  a  gas  flame  within  the  cylindrical  case.  The 
link,  B,  operates  the  levers,  A  and  D,  so  as  to  open  the  valve,  E,  which 
is  normally  held  closed  by  the  spring,  C,  bearing  on  its  rod  as  shown. 
In  opening  the  valve  to  the  point  in  the  cycle  at  which  the  cam  actuates 
the  link,  B,  thus  compressing  the  spring,  C,  and  opening  the  valve,  D, 
the  interior  of  the  hot  tube,  G,  is  brought  into  communication  with 
the  combustion  chamber,  F,  of  the  cylinder.  The  time  of  ignition  may 
be  varied  by  adjusting  the  throw  of  the  cam,  so  as  to  bring  the  opening 
of  the  valve,  E,  to  any  desired  point. 

it  causes  either  premature  ignition  or  missed  fire,  on  account  of 
the  presence  of  burned-out  gases  within  it.  Under  some  condi- 
tions, it  is  stated,  the  tube  is  so  filled  from  end  to  end  with  these 
residua  that  the  charge  in  cylinder  cannot  come  into  contact  with 
the  incandescent  walls,  in  order  to  ignite  properly.  Under  other 
circumstances  the  tube  is  clogged  with  dead  gases  from  its  closed 


METHODS  OF  IGNITION. 


265 


end  nearly  to  the  cylinder,  and,  when  this  condition  is  coupled 
with  the  fact  that  the  heated  portion  is  too  near  the  entrance, 
premature  ignition  results  before  the  completion  of  the  com- 
pression stroke.  Although  these  results  may  follow  in  a  given 
type  of  engine,  it  is  necessary  to  note  several  things :  i.  The  tube 
should  be  so  constructed  that  the  flame  plays  on  that  portion 
of  its  length  which  has  been  found  to  be  at  most  suitable  dis- 
tance from  the  opening,  not  risking  the  danger  of  premature 
ignition,  if  it  follows  from  such  a  cause  only.  2.  The  tube  should 
be  heated  to  the  proper  temperature  to  secure  the  best  and  quick- 


-n- 


FIG.  181.— Diagram  of  a  Primary  Spark  Circuit,  equipped  with  a  Dynamo 
and  Storage  Battery.  The  dynamo  may  be  used  to  spark  the  engine 
and  supply  the  battery  at  the  same  time,  or  to  perform  the  former 
function  exclusively.  The  battery  is  charged  when  the  switch  between 
it  and  the  dynamo  is  thrown  in.  If  the  other  switch  is  connected  at  the 
point  marked  "dynamo"  in  the  cut.  As  is  obvious  from  the  cut,  the 
dynamo  may  be  cut  out  altogether,  allowing  the  storage  battery  to 
supply  current  for  sparking  purposes.  When  both  switches  are  in,  the 
storage  battery  will  supply  current  for  sparking,  until  the  dynamo  has 
attained  its  full  speed. 

est  ignition.  3.  The  temperature  being-  properly  arranged,  the 
burned-out  gases  should  be  largely  expelled  from  the  tube  by 
their  own  expansion  under  heat.  4.  The  compression  ratio 
should  be  such  that  the  fuel  charge  may  be  forced  into  the  tube 
at  the  proper  point,  in  spite  of  and  against  the  expanding  ten- 
dency of  dead  gases  clogging  its  interior.  With  a  well-made  tube, 
a  properly  adjusted  compression  an,d  a  powerful  jet  flame,  there 
is  no  reason  for  such  accidents  as  are  above  mentioned.  They 
result  rather  from  faulty  construction  or  bad  management,  and 
are  not  the  necessary  faults  of  the  apparatus. 


266  SELF-PROPELLED    VEHICLES. 

On  Electrical  Ignition  Systems. — Although  some  effective 
types  of  automobile  gasoline  engines  still  use  the  hot-tube  igni- 
tion, the  larger  majority  are  equipped  with  some  form  of  elec- 
tric-sparking device.  This  method  has  the  advantage  of  pro- 
viding an  entirely  intermittent  source  of  ignition,  and  of  being 
much  more  flexible  than  any  constantly  existing  source  of  heat, 
such  as  found  in  hot  walls  or  tubes,  thus  being  susceptible  of  a 
nearly  perfectly-timed  ignition.  The  electric-sparking  system, 
of  course,  requires  some  separate  source  of  electrical  energy,  such 
as  a  battery  of  galvanic  cell,  a  small  dynamo,  or  a  magneto-gen- 
erator. The  current  thus  generated  is  used  to  produce  a  spark, 
either  from  a  primary  or  a  secondary  circuit;  the  former  con- 
taining the  ordinary  reaction  coil  and  producing  a  low-tension 
spark,  from  either  a  wiping  or  a  breaking  contact ;  the  latter  con- 
taining an  induction  coil  and  producing  a  high-tension  spark  be- 
tween slightly  separated  terminal  points.  The  latter  variety  is 
commonly  known  as  the  "jump-spark."  The  sparks  of  both 
varieties  are  successfully  used  in  motor  carriages,  although  the 
high-tension  circuit  and  the  jump  spark  seems  to  be  the  favorite. 

Sources  of  Current:  Chemical  Cells. — The  general  plan  with 
electrical  ignition  circuits,  producing  a  spark  from  a  secondary 
current,  is  to  use  some  form  of  chemical  dry-cell  battery.  Such 
chemical  cells  are  necessarily  of  the  open-circuit  variety,  since  it 
would  not  be  practicable  to  periodically  interrupt  the  current  from 
a  closed  circuit  cell  without  using  much  more  complicated  ma- 
chinery, and  wasting  an  immense  percentage  of  the  total  output. 
There  are  numerous  open-circuit  dry  cells  that  are  suitable  for  use 
in  connection  with  the  ignition  circuits  of  gasoline  vehicles ; 
but  it  is  not  necessary  to  dwell  upon  their  construction  and  prop- 
erties, since  the  sole  requirements  seem  to  be  reasonable  dura- 
bility and  an  average  good  output  capacity ;  such  cells  rated  from 
i  to  i  y*  volts,  are  connected  in  batteries  of  three  or  four,  so  as  to 
be  capable  of  producing  a  current  of  the  amperage  required  in  any 
given  case. 

Storage  Batteries. — With  several  makes  of  carriage,  par- 
ticularly such  as  are  driven  by  high-powered  motors,  small  stor- 
age cells  are  used  as  a  source  of  current.  The  size  most  effective 
for  this  work  is  the  40  ampere-hour,  which  furnishes  current 


METHODS  OF  IGNITION.  267 

sufficient,  either  for  the  continuous  ignition  of  the  motor  or  for 
starting,  with  a  small  dynamo  or  magneto,  being  then  cut  out  by 
an  automatic  switch.  As  the  general  theory,  construction  and 
management  of  storage  batteries  are  outlined  in  a  later  chapter, 
it  will  be  necessary  to  say  little  here  regarding  them.  The  fact 
that  a  storage  cell  must  be  periodically  charged  from  a  source  of 
direct  current  renders  its  use  somewhat  more  troublesome  than 
that  of  a  primary  cell.  It  has  the  great  advantage,  however,  that, 
unlike  any  type  of  primary  cell  it  may  be  renewed  or  recharged 
when  the  current  gives  out.  When  a  direct  current  is  available 
from  street  lighting  or  power  mains,  no  switchboard  or  rotary 
converter  is  required  for  charging,  as  is  necessary  with  the  bat- 
teries used  in  propelling  electric  carriages. 


FIG.  182.— Section  through  a  Type  of  American  Storage  Cell  used  for  Gas 
Engine  Ignition.  The  parts  are:  Positive  binding  post  (1);  negative 
binding  post  (2) ;  rubber  stopper  (3) ;  vent  tube  (4) ;  outer  metal  case  (b) ; 
lead  lining  (6) ;  hard  rubber  insulator  (7) ;  positive  element  (8) ;  negative 
element  (9) ;  sealing  compound  (10) ;  hard  rubber  jar  (11)  positive  ter- 
minal (12) ;  negative  terminal  (13) ;  the  fluid  or  electroloyte  (14). 

FIG.  183.— Holtzer-Cabot  Horizontal  Magneto-Generator,  used  in  the  spark- 
ing circuits  of  gas  engines.  This  machine  is  built  on  the  same  plan  as 
the  vertical  magneto  shown  in  Fig.  184;  but  to  meet  the  requirements 
of  many  motor  vehicle  engines,  is  mounted  as  shown,  in  order  to  be 
more  readily  adopted  to  a  limited  space. 

Magneto=Generators  and  Dynamos. — With  gasoline  vehicles 
using  a  primary  sparking  circuit,  the  source  of  electrical  energy, 
except  in  starting,  is  practically  always  some  form  of  small 
dynamo  or  magneto-generator.  The  primary  distinction  between 
these  two  forms  of  electrical  source,  as  the  words  are  generally 
used,  is  that  the  magneto-generator  has  a  permanent  magnetic 


268 


SELF-PROPELLED   VEHICLES. 


field,  being  composed  of  several  permanent  magnets,  in  the  field 
of  which  is  a  rotating  shuttle-wound  armature.  The  word  dyna- 
mo, on  the  other  hand,  is  commonly  used  to  designate  a  mechani- 
cal source  of  electrical  energy,  having  a  separately  excited  mag- 
netic field,  consisting  of  an  even  number  of  pole  pieces  or  cores, 
each  of  which  is  wound  with  a  suitable  length  of  insulated  wire, 
connected  in,  series  to  another  length  of  opposed  polarity  through- 
out the  entire  circuit  of  the  field.  Between  these  pole  pieces  ro- 
tates an  armature  composed  of  a  drum  or  a  bar  supporting  a  num- 
ber of  thin  insulated  metal  discs,  which  are  wound  about  with  a 


FIG.  184.— A  Typical  Magneto  Generator— the  Holtzer-Cabot  Vertical  Stan- 
dard. The  machine  here  shown  is  similar  in  all  its  details  to  the  former, 
but  is  built  in  larger  proportions  and  gives  a  more  powerful  output  in 
E.  M.  F. 

suitable  length  of  insulated  wire,  the  two  terminals  being  con- 
nected through  the  commutator  to  the  outside  circuit,  which  be- 
gins and  ends  at  the  commutator  brushes.  As  the  theory  and 
construction  of  a  dynamo  are  given  later,  they  need  not  be  treated 
here. 

The  Construction  of  a  Magneto-Generator. — The  common- 
est form  of  magneto-generator  consists  of  two  or  more  horse- 


METHODS  OF  IGNITION. 


269 


shoe  magnets  set  in  suitable  pole  pieces,  between,  which  rotates 
a  shuttle-shaped  armature  wound  about  with  a  suitable  length  of 
fine  insulated  wire.  As  may  be  seen  in  the  accompanying  illus- 
tration, the  lines  of  force  extending  between  the  poles  of  the 
magnets  are  variously  distributed  according  to  the  point  occupied 
by  the  armature  in  its  rotation.  It  may  thus  be  understood  that 
any  movement  of  the  armature  on  its  spindle,  either  in  making  a 
complete  revolution  or  in  oscillating  backward  and  forward,  must 
operate  to  deflect  and  distort  these  lines  of  force  in  such  a  man- 


PIG.  185.— Diagram  of  the  Construction  and  Theoretical  Operation  of  a 
Typical  Magneto-Generator.  Between  the  prongs  of  the  horsehoe  mag- 
nets, the  shuttle-shaped  armature,  shown  at  the  centre  of  the  figure, 
rotates  on  a  suitable  spindle.  This  armature  is  wound  from  end  to 
end  with  insulated  wire,  so  that  when  rotated  a  powerful  current  is 
produced  in  the  windings  by  cutting  the  magnetic  lines,  whose  varying 
strength  is  shown  by  the  shaded  portions  in  the  two  views.  When  the 
armature  is  in  the  position  shown  in  the  first  diagram,  the  lines  of 
force  mostly  converge  at  the  top  and  bottom,  finding  a  direct  path 
through  the  metal  and  flanges  of  the  shuttle.  When  in  the  position 
shown  in  the  second  diagram,  the  lines  are  converged  so  as  to  pass 
through  the  metallic  core  of  the  armature;  the  most  direct  path  being 
chosen  in  both  cases. 


ner  as  to  set  up  powerful  induced  currents  in  the  armature  wind- 
ing. Since,  however,  the  paths  of  the  magnetic  forces  are  thus 
continually  shifted  from  the  lines  of  the  least  resistance  to  the 
lines  of  the  greatest  resistance,  it  follows  that  the  current  de- 
livered from  the  terminal  connections  will  have  a  constantly 
shifting  potential,  and  will  hence  be  an  alternating  current — that 
is  to  say,  a  current  flowing  first  in  one  direction  and  then  in  an- 
other. This  is  the  very  thing  that  is  required  in  telephone  circuits, 


270  SELF-PROPELLED   VEHICLES. 

in  which  magneto-generators  are  commonly  used  to  generate  a 
current  for  operating  the  switchboard  drops  and  transmitting 
call-bell  signals.  For  this  purpose,  one  end  of  the  armature  wind- 
ing is  connected  to  the  centre  of  the  rotating  spindle,  which  is 
insulated ;  the  other  to  the  frame  of  the  machine.  Generators 
of  precisely  similar  construction  and  wiring  may  be  used  for  gas- 
engine  ignition,  provided  the  cut-off  of  the  current  be  timed  to 
occur  at  precisely  the  point  of  highest  potential  or  greatest  in- 
tensity, which  is  to  say,  when  the  longitudinal  flange  pieces  of  the 
shuttle-shaped  armature  are  in  a  vertical  position.  For  ordinary 
ignition  circuits,  however,  the  alternating  current  is  not  used,  and 
consequently  the  magneto  is  equipped  with  a  rotating  commutator 
and  terminal  brushes,  such  as  are  used  on  direct-current  dynamos. 

The  Operation  of  a  Magneto=Generator. — The  general  oper- 
ation of  the  magneto-generator  depends  upon  a  few  obvious  prin- 
ciples of  construction,  which  we  may  sum  up  under  the  following 
heads:  i.  The  quantity  of  the  current  depends  upon  the  strength 
of  the  magnetic  field  and  the  number  of  lines  of  force  passing 
through  the  armature.  2.  The  electromotive  force  produced 
depends  for  its  amount  upon  the  length  of  the  armature  winding, 
and  the  rapidity  with  which  the  armature  is  rotated,  cutting  and 
deflecting  the  lines  of  magnetic  force.  If  the  armative  be  wound 
with  comparatively  thick  wire,  which  would  give  a  short  winding, 
the  E.  M.  F.  will  be  low ;  but  if  it  be  wound  with  a  finer  wire, 
giving  a  much  greater  length,  the  E.  M.  F.  will  be  higher,  in 

ratio  to  the  diameters  of  the  wires  used. 

• 

A  Stationary  Armature  Magneto-Generator. — Although 
most  of  the  magneto-generators  manufactured  for  use  in  igniting 
gas  engines  conform  to  the  general  characteristics  of  the  ma- 
chines just  described,  an  interesting  variation  is  found  in  the 
Bosch  &  Simms  stationary  armature  generator,  which  operates 
without  a  commutator,  the  terminals  being  connected  to  the  out- 
side circuit,  as  in  the  ordinary  telephone  magneto.  The  armature 
of  this  machine  is  shuttle-shaped  and  wound  with  insulated  wire 
as  already  described,  but  it  is  fixed  rigid  at  one  end  in  such  po- 
sition that  the  lines  of  magnetic  force  strike  directly  through  the 
insulated  coil  of  the  winding.  The  armature,  however,  is  of 
somewhat  smaller  relative  diameter  than  is  used  on  the  other 


METHODS  OF  IGNITION. 


271 


types  of  magnetos,  in  order  to  leave  a  clearance  for  an  interven- 
ing sleeve  or  open-sided  cylinder  of  soft  iron  to  be  oscillated  on 
the  same  axis  between  it  and  the  pole  pieces.  This  sleeve  is 
caused  to  oscillate  through  about  one-half  a  revolution  by  the 
connecting  rod  and  crank  geared  to  an  adjustable  cam  on  the 
secondary  shaft  of  the  engine,  the  difference  in  throw  between 
the  crank  geared  to  the  spindle  of  the  sleeve  and  the  radius  of 
the  cam  operating  to  prevent  a  full  revolution.  This  cam  also 
operates  to  break  the  circuit  at  the  contact  points  within  the 
cylinder,  at  a  predetermined  point  in  the  stroke,  which  is  always 
made  to  occur  at  precisely  the  point  when  the  oscillating  sleeve 


FIG.  186.— Diagram  of  the  Construction  and  Operation  of  the  Simms-Bosch 
Igniting  Magneto.  In  this  machine  the  armature  is  stationary,  the 
lines  being  cut  by  an  open  sleeve  rotating  between  it  and  the  field 
pieces.  The  first  diagram  shows  the  convergence  of  the  lines  of 
force  before  the  rotating  sleeve  has  been  inserted;  the  second  shows 
the  lines  when  the  sleeve  is  directly  across  the  magnetic  lines;  the  third, 
where  the  sleeve  is  in  position  at  oblique  angles  to  the  lines.  As  may 
be  understood,  this  arrangement  produces  a  very  powerful  variation  of 
the  field  and  a  very  strong  output  of  E.  M.  F. 

is  in  position  to  cut  through  the  greatest  number  of  magnetic 
lines,  thus  producing  the  maximum  E.  M.  F.  The  spark  may 
be  advanced  by  a  feather  on  the  cam,  and  a  spiral  groove  cut  on 
its  spindle,  so  that  when  it  is  moved  lengthwise  the  operation  of 
the  contact  breaker  may  be  varied,  although  maintaining  the 
sparking  point  at  the  same  maximum  position  of  the  oscillated 
sleeve.  The  positive  terminal  is  on  an  insulated  binding  screw 
at  the  top  of  the  armature,  the  path  of  the  return  current  being 
through  the  metal  of  the  engine  cylinder,  to  the  base  of  the  mag- 
neto-generator. In  general,  the  method  adopted  for  driving  the 


2T2 


SELF-PROPELLED  VEHICLES. 


rotating  portion  of  the  magneto  is  to  connect  it  direct  to  the  fly- 
wheel of  the  engine,  either  by  a  belt  or  a  brushing  roller.  With 
this  arrangement  it  has  usually  been  found  that  a  current  suf- 
ficient to  begin  sparking  may  be  produced  by  the  act  of  turning 
over  the  flywheel  to  start  the  motor. 

The  Primary  Spark. — The  primary  spark  is  so  called  because 
it  is  produced  on  a  primary  circuit,  as  distinguished  from  one 
occurring  on' a  secondary  circuit,  or  a  circuit  in  which  a  current  is 


FIG.  187.— Sectional  Diagram  of  the  Apple  Igniting  Dynamo.  The  parts 
shown  are:  A,  cast  iron  body  containing  the  moving  parts;  B,  the  hinged 
lid  of  the  body;  C,  the  one-pole  piece  of  the  field  magnets;  D,  the  arma- 
ture; E,  the  coil  of  one  of  the  field  magnets;  F,  brass  bearing  of  the 
armature  spindle;  G  and  H,  fibre  tubes  surrounding  the  spindle;  K, 
brass  spider  supporting  the  spindle;  L,  commutator;  M,  wick  feed  oil 
cup;  N,  beveled  nut  supporting  the  commutator;  O,  P,  Q,  supports  of 
the  commutator;  R,  the  driving  disc;  S,  lever  friction  pinion.  This 
machine  can  generate  a  direct  current  at  8  volts  at  a  speed  of  between 
1,000  and  1,200  revolutions  per  minute.  It  is  provided  with  a  simple 
centrifugal  governor  that  automatically  interrupts  the  driving  con- 
nections when  a  certain  speed  has  been  exceeded. 

induced,  as  in  an  induction  coil,  by  a  make  and  break  of  the  bat- 
tery circuit,  as  will  be  subsequently  explained.  While  it  is  pos- 
sible to  produce  a  small  spark  by  simply  breaking  a  battery  cir- 
cuit, it  is  necessary  in  order  to  have  a  spark  of  sufficient  intensity 
and  duration,  to  introduce  an  effect  of  self-induction.  This  is  done 
by  passing  the  direct  curren/t — generally  from  a  commutated 
magneto — through  the  winding  of  a  long-wound  magnetic,  or 
reactance  coil.  The  spark  coil  used  in  this  method  of  ignition 
consists  of  a  long  iron  core  wound  with  a  considerable  length  of 


METHODS  OF  IGNITION. 


low-resistance  copper  wire ;  the  length  of  the  core  and  the  number 
of  turns  of  the  insulated  winding  determining  the  efficiency. 
The  current  passing  through  the  winding  magnetizes  the  iron, 
and  a  self-induced  current  is  generated,  which  is  occasioned  by 
and  superposed  on  the  battery  current.  As  soon  as  the  circuit 
is  broken,  the  magnetic  reactance  tends  to  continue  the  flow  of 
current,  despite  the  gap,  and  occasions  a  spark  of  great  heat  and 


FIG.  188.— Diagram  of  the  Simms  Magneto  and  Primary  Sparking  Circuit. 
A  is  the  metal  base  mounting  the  sparking  contacts;  B,  a  hammer  head 
on  rod,  D,  for  actuating  bell  crank  against  tension  of  spring,  separat- 
ing electrodes;  E,  rotating  notched  cam  on  shaft,  F;  G,  connecting  rod 
for  oscillating  sleeve  let  over  armature;  H,  H,  magnets;  K,  pole  piece; 
J,  base  plate  of  magnets. 

brilliancy.  The  spark  occurs  at  the  moment  of  breaking  the  cir- 
cuit, not  at  the  moment  of  making  With  high  speed  engines  a 
shorter  core  is  used  on  the  coil,  the  effect  of  a  smaller  magnetic 
lag  being  thus  obtained. 

Typical  Means  for  Producing  a  Primary  Spark.— There  are 
two  typical  methods  of  producing  a  primary  spark  :  ( i )  by  wiping 


274 


SELF-PROPELLED   VEHICLES. 


contact,  in  which  one  of  the  electrodes  is  constantly  rotated,  and 
(2)  by  breaking  contact,  in  which  one  electrode  is  drawn,  away 
from  the  other  at  the  proper  moment  for  the  spark.  A  common 
form  of  wiping-spark  device  is  shown  in  an  accompanying  figure. 
Here  the  two  electrodes,  X  and  Y,  the  latter  of  which  is  set  in  an 
insulating  plug,  screwed  into  the  wall  of  the  combustion  space, 
electrical  connection  being  made  by  the  wire  shown  at  D.  The 
electrode,  X,  is  a  rotating  spindle,  deriving  it  motion  from  the 


FIG.  189.— Details  of  a  Common  Form  of  Contact  for  Producing  a  Wiping 
Spark.  The  electrode,  X,  rotated  by  the  crank,  E,  as  indicated,  gives 
a  wiping  contact  and  break  at  the  terminal,  Y,  which  is  tipped  by  a 
resiliant  platinum  spring.  One  of  the  wires  forming  the  circuit  is  con- 
nected at  D  through  the  insulated  plug  screwed  into  the  body  of  me 
ignition  chamber;  the  other  is  connected  to  the  metal  of  the  chamber 
at  the  nut,  M.  The  advantage  of  this  form  of  sparking  device  is  that 
the  constant  contact  of  the  electrode  keeps  the  surfaces  clean,  but  at 
the  same  time  the  constant  friction  produces  an  immense  wear  for  the 
same  reason.  An  excellent  form  of  simple  make-and-break  device  is 
shown  in  connection  with  the  suction  of  the  Duryea  cylinder  in  a  suc- 
ceeding chapter. 

FIG.  190.— The  Apple  Magnetic  Ignition  Plug  for  Producing  a  Primary 
Spark.  The  two  electrodes,  as  shown,  are  normally  in  contact,  the  coil 
contained  within  the  cylindrical  shell  of  the  plug  acting  as  a  magnet 
to  break  the  contact  at  the  required  point.  As  claimed  by  the  manu- 
facturers, the  advantages  of  this  device  are  ready  adjustment  and 
repair,  a  ready  cleansing  of  the  contacts,  and  the  avoidance  of  any 
other  coil  than  is  used  within  the  plug  itself.  The  spark  can  also  be 
controlled  from  the  outside,  the  same  as  with  the  jump  -  spark  coil, 
with  the  combined  advantage  of  much  greater  simplicity  of  parts  and 
circuit  arrangements. 

link  and  small  crank  shown  at  E,  and  forming  the  other  terminal 
of  the  circuit,  through  the  wire  connected  to  the  ,nut,  M.  On 
the  end  of  the  terminal,  Y,  is  a  resilient  spring  of  platinum,  which 
forms  a  contact  with  the  electrode,  X,  and  enables  a  spark  to  be 
formed  whenever  the  contact  is  broken  by  its  rotation.  .This 
method  of  periodically  breaking  the  contact  is  so  varied  in  sev- 
eral types  of  gas  engine  that  the  simple  make-and-break  device, 


METHODS  OF  IGNITION. 


2T5 


positively  operated,  is  substituted  for  the  wiping  contact  of  the 
rotating  electrode.  The  advantages  of  the  wiping  contact  are 
that  the  surfaces  of  the  electrodes  are  constantly  wiped  clean  of 
any  impurities  produced  by  the  combustion  of  the  fuel  charge 
in  the  cylinder.  It  has,  however,  an  even  greater  disadvantage 
involved  in  the  enormous  wear  of  the  small  points  due  to  con- 
stant friction.  The  simpler  make-and-break  device,  on  the  other 
hand,  while  producing  quite  as  good  a  spark,  permits  no  really 
reliable  method  of  preventing  the  deposit  of  carbonized  particles, 
which  weaken  and  eventually  choke  the  spark. 

The  most  widely  famous  primary  ignition  systems  are  those 
used  on  the  early  Mors  carriage  motors  and  the  Simms  &  Bosch 


FIG.  191.— The  Duryea  Primary  Spark  Ignition  Apparatus.  A  is  the  ex- 
haust valve;  D,  the  exhaust  valve  stem;  T,  the  stem  of  the  sparker 
hammer,  journaled  in  the  stem,  D;  E,  the  exhaust  slide;  F,  roller  at 
end  of  E;  G,  the  rotating  exhaust  cam;  H,  exhaust  valve  spring;  J,  a 
clamp  fixed  in  position  by  a  set  screw;  M,  pivoted  lift  that  trips  the 
hammer,  L,  operated  by  roller,  N,  beside  the  exhaust  cam,  knocking 
the  sparker,  T.  away  from  the  insulated  plug,  O.  U  is  the  inlet  valve; 
V,  the  throttle  slide;  S,  spring  controlling  the  opening  of  U;  W,  the 
spark  coil;  R,  the  metal  union  nut,  clamping  O  in  place. 

system,  already  noticed.  Among  the  best  knowri,  makes  of  Amer- 
ican gasoline  carriage  motors  using  the  primary  spark  may  be 
mentioned  the  Duryea  and  Haynes-Apperson. 

The  Duryea  make-and-break  apparatus  closely  resembles  the 
Mors.  The  current  is  carried  to  the  engine  by  a  bare  wire  at- 
tached to  aiti  insulated  stem  by  a  spring  clip,  which  is  caused  by 
vibration  to  grip  tighter,  thus  insuring  a  constant  contact. 
Around  the  middle  of  this  insulated  stem  is  a  flange,  on  both  sides 
of  which  ordinary  mica  washers  are  placed.  A  metal  union  nut 
or  cap  binds  the  mica  washers  and  the  stem  to  the  base  of  the 
plug,  which  in  turn  screws  into  the  cylinder  wall,  allowing  the 
end  of  the  plug  to  project  inside.  This  end  is  tipped  with  a  ring 


276 


SELF-PROPELLED   VEHICLES. 


of  nickel  alloy,  which  resist  both  heat  and  corrosion  better  than 
other  metals,  and  can  be  turned  around  when  worn.  .The  mica 
insulation  is  not  exposed  to  soot,  oil  and  burned  gases,  and  keeps 
clean  for  hundreds  or  even  thousands  of  miles.  The  union  nut  or 
cap  can  be  unscrewed  quickly,  exposing  the  mica  and  permitting 
the  dirty  one  to  be  removed.  Through  the  hollow  exhaust  valve 
stem  a  sparker  stem  is  inserted  having  conical  ground  joints  in 


FIG.  192.— A  Primary  Spark  Ignition  Circuit,  containing  a  magneto-gener- 
ator, an  8-cell  chemical  battery,  and  an  automatic  cut-off  or  relay.  The 
chemical  battery  is  used  to  supply  the  current  for  producing  the  spark 
until  the  magneto-generator  has  attained  its  required  speed.  At  that 
point  the  current  from  the  generator  passing  through  the  coil  of  the 
automatic  switch  is  sufficiently  strong  to  cause  the  magnets  of  the  relay 
to  attract  their  armature  and  cut  the  circuit  of  the  chemical  battery. 
This  circuit  may  also  be  cut  out  at  any  time  desired  with  the  single 
point  hand  switch. 

the  exhaust  valve  seat,  and  with  bent  point  or  arm  nickel  tipped 
and  adapted  to  contact  against  the  insulated  nickel  ring.  The 
projecting  outer  end  of  this  sparker  stem  is  provided  with  a 
hammer  spring  and  clamp,  the  latter  being  held  by  a  set  screw 
firmly  on  the  stem.  A  flat  lift  raised  by  a  roller  on  the  exhaust 
cam,  raises  the  hammer  and  permits  it  to  drop  suddenly  under 
the  action  of  the  spring,  causing  it  to  strike  the  clamp  and  knock 


METHODS  OF  IGNITION.  2YT 

the  sparker  point  out  of  the  engagement  until  the  lift  is*  again 
operated.  The  exhaust  cam  pushes  the  exhaust  valve  with  the 
sparker  parts  out  of  the  way,  so  that  the  lift  may  return  to  its 
original  position,  ready  to  repeat  the  operation.  This  mechanism 
is  quite  simple  amd  is  located  on  top  of  the  motor  in  a  most-  ac- 
cessible position*. 

With  every  variety  of  primary  sparking  circuit  the  most  avail- 
able means  for  timing — advancing  or  retarding — the  spark  is 
some  device  for  rotating  the  throw  of  the  actuating  cam  through 
part  of  a  revolution  in  the  one  direction  or  the  other.  This  may 
be  done  by  placing  the  cam  on  a  sleeve,  to  which  a  twist  may  be 
imparted,  either  from  a  centrifugal  governor  or  by  a  hand-oper- 
ated gear.  Advocates  of  the  primary  spark  claim  that  it  is  quite 
as  reliable  and  serviceable  for  ignition  as  the  secondary  or  jump 
spark,  while  not  requiring  the  complication  of  an  induction  coil, 
condenser  and  trembler,  and  doing  away  entirely  with  the  troubles 
involved  in  the  use  of  plugs.  It  is,  however,  less  flexible,  as  or- 
dinarily produced,  and  so  has  been  discarded  for  the  high-tension 
apparatus  by  the  majority  of  high-powered  carriage  builders. 

Properties  of  the  Jump-Spark. — With  the  jump-spark  pro- 
duced from  a  secondary  circuit,  there  are  no  movements  of  the 
electrodes,  the  primary  circuit  being  periodically  broken  by  a 
positively  operated  circuit-breaker,  which  thus  induces  an  in- 
termittent current  of  varying  intensity  in  the  secondary.  The 
electrodes  are  usually  contained  in  a  device  known  as  a  sparking- 
plug,  in  which  they  are  insulated  from  one  another,  by  the  use 
of  porcelain,  mica  or  other  suitable  substance.  The  most  com- 
mon objection  to  the  use  of  the  jump-spark  is  found  in  the  fact 
that  particles  of  carbon  dust,  produced  by  the  combustion  of  the 
fuel  charge,  are  deposited  between  the  small  sparking  points,  thus 
preventing  the  formation  of  a  spark,  by  filling  up  the  gap,  across 
which  the  current  is  obliged  to  leap  in  forming  the  spark. 

In  order  to  obtain  a  secondary  current  with  the  use  of  a  chemi- 
cal battery  or  direct  current  mechanical  generator,  it  is  necessary 
to  interrupt  the  primary  circuit  at  timed  intervals.  There  are  two 
methods  by  which  this  is  accomplished :  ( I )  by  the  use  of  a  snap 
cam  that  once  in  every  revolution  brings  together  the  terminals 
of  the  circuit;  (2)  by  the  use  of  a  wipe-contact  interrupter,  or 
"commutator,"  and  a  magnetic  trembler  at  one  pole  of  the  coil 


278  SELF-PROPELLED    VEHICLES. 

core.  'Only  a  very  rudimentary  knowledge  of  electrical  apparatus 
is  required  to  make  it  evident  that  snap  cam  and  trembler 
cannot  be  advantageously  used  in  the  same  circuit.  The  two 
varieties  of  apparatus  are  very  well  shown  by  the  two  typical 
circuits,  the  De  Dion  and  Benz.  Both  of  them  also  ilkvstrate  the 
prevailing  method  of  grounding  the  negative  lead  of  the  second- 
ary circuit  to  the  metal  of  the  engine.  The  general  principles  are 
explained  with  single  cylinders,  but  multiple  cylinder  arrange- 
ments are  shown  later. 

The  De  Dion  &  Bouton  Jump=Spark  Circuit. — Very  nearly 
the  typical  arrangement  for  the  high-tension  jump-spark  circuit 
is  that  used  on  the  De  Dion  &  Bouton  carriages.  The  general 
plan  of  the  connections  is  shown  in  an  accompanying  diagram, 
where,  as  may  be  seen,  the  current  produced  by  a  chemical  bat- 
tery is  passed  through  the  primary  winding  of  the  induction  coil, 
the  circuit  being  periodically  broken  by  a  vibrating  trembler  or 
contact  breaker,  the  details  of  which  are  also  given.  The  positive 
pole  of  the  battery  is  connected  to  the  primary  winding  of  the 
induction  coil,  the  opposite  terminal  of  which  is  connected  to  the 
lower  of  the  two  binding  screws  attached  to  the  vulcanite  base  of 
the  contact  breaker.  The  negative  pole  is  grounded  to  the  frame 
of  the  carriage  and  thence  the  metal  of  the  motor  cylinder,  the  cir- 
cuit being  completed  by  a  wire  connecting  with  the  upper  binding 
post  on  the  contact  breaker.  The  operation  of  this  contact 
breaker  is  obvious.  It  consists  of  a  positively  operated  cam  on 
the  two  to  one  shaft,  of  round  contour  except  for  an  irregular  sec- 
tor-shaped notch  in  its  circumference,  which  allows  the  point  of 
the  trembler,  T,  to  drop  when  the  notch  meets  it  in  the  rotation 
of  the  cam,  thus  making  contact  from  the  terminal,  B,  and 
the  upper  bindkig  post  on  the  base  of  the  apparatus,  with 
the  negative  pole  of  the  battery,  and  the  screw,  d,  which  is  con- 
nected through  the  lower  binding  post  with  the  positive  pole  of 
the  battery,  as  already  explained.  By  this  means,  the  circuit 
being  periodically  broken,  a  powerful  high-tension  current  is 
produced  in  the  secondary  winding  of  the  induction  coil,  one 
terminal  of  which  is  connected  with  the  insulated  portion  of  the 
sparking  plug,  the  other  with  the  metal  of  the  cylinder;  the 
spark  being  produced  between  the  terminal  contacts  of  the  plug 
at  every  interruption.  By  this  arrangement  of  the  circuit  the 


METHODS  OF  IGNITION. 


279 


FIG.  193.— Diagram  of  the  De  Dion  Jump-Spark  Ignition  Circuit.  A  is  a 
battery  of  four  cells,  one  pole  of  which  is  connected,  as  shown,  to  the 
tubular  frame  of  the  carriage  at  the  point,  N,  the  circuit  being  thus 
completed  through  the  steel  frame  work  to  binding  post,  L,  on  the 
circuit  breaker;  thus,  the  circuit  is  made  by  the  contact  of  the  trem- 
bler, T,  with  the  point  of  the  screw,  D,  on  the  post,  V,  through  binding 
post,  K  to  M,  thus  through  the  primary  winding  of  the  induction  coil 
and  to  the  oposite  pole  of  the  batery.  The  secondary  circuit  joined  by 
one  pole  of  the  condenser,  D,  is  connected  to  one  end  of  the  sparking 
plug,  P,  the  other,  being  grounded  to  the  frame,  completes  the  circuit 
by  the  metallic  contacts  with  the  body  of  the  motor,  as  indicated  by 
the  dotted  line. 

electrical  potential  of  the  secondary  circuit,  and  therefore  of  the 
grounded  point  of  the  sparking  plug,  are  reduced  to  the  lowest 
value,  the  negative  terminal  of  the  battery  affording  a  constant 


280 


SELF-PROPELLED   VEHICLES. 


dead  ground  at  a  much  lower  potential  than  may  even  be  found  in 
the  metal  base  of  the  machine  as  a  whole*  On  the  closing  of  the 
primary  circuit  through  the  contact  spring,  as  already  described, 
the  current  in  the  primary  winding  of  the  induction  coil  rises 
rapidly  to  its  full  value  against  the  opposing  self-induced  current 
generated  in  the  coil,  and  establishing  a  powerful  magnetic  field, 
whose  lines  of  force  intersect  the  plane  of  the  convolutions  in 


FIG.  194.— The  De  Dion  &  Bouton  Single  Cylinder  Circuit  Breaker.  B, 
platinum-ended  screw;  C,  notched  cam;  M,  terminal  in  contact  with  B 
and  Q;  N,  wire  terminal  in  contact  with  P,  S  and  T;  P,  stud  supporting 
the  trembler;  Q,  split  projecting  stud  supporting  the  platinum-tipped 
screw,  B;  R,  screw  to  make  Q  grip  B;  K,  screw  fastening  trembler,  T, 
to  base,  P;  T,  the  trembler  spring. 

FIG.  195.— Contact  Breaker  of  the  Minerva  Single-Cylinder  Tricycle.  A, 
rotating  cap  on  end  of  secondary  shaft,  carrying  point  to  left  trembler, 
B;  X,  cam  to  lift  valve  stem;  C,  C,  screws  connecting  trembler  spring  to 
frame;  D,  stud  of  platinum  making  contact  with  tip  of  E;  F,  mica 
sheet;  G,  brass  screw  holding  one  end  of  the  circuit  wire;  K,  exhaust 
valve  lift;  L,  stem  sliding  inside  of  tube,  M,  secured  to  plate,  N;  H,  ring 
for  holding  wire  screwed  at  G;  J,  pivot  for  rod  moving  contact  breaker 
through  arc  from  position  shown  to  that  indicated  by  dotted  outlines. 

the  secondary  circuit,  creates  therein,  during  the  brief  period 
when  the  battery  current  is  flowing,  a  constantly  increasing  dif- 
ference of  electrical  pressure  between,  the  grounded  secondary 
terminal  and  the  opposed  extremity  of  the  same  winding.  The 
difference  of  electrical  pressure,  resulting  from  the  increasing 
density  of  the  magnetic  field,  is  not  great  enough,  however,  to 
cause  a  spark  discharge  between  the  points  of  the  plug,  owing 


METHODS  OF  IGNITION. 


281 


to  the  fact  that  the  range  of  change  in  the  density  of  the  mag- 
netic field  is  retarded  by  the  self-induction  of  the  primary  cir- 
cuit opposing  the  rapid  flow  of  the  battery  current.  A  condenser 
is  therefore  used,  one  pole  of  which  is  connected  to  the  primary 
terminal,  wired  to  the  lower  binding  post  of  the  contact  breaker 
and  thus  to  the  screw,  D,  already  mentioned,  the  other  being 
connected  to  the  grounded  terminal  of  the  secondary  circuit.  By 
this  means  the  'magnetic  field  produced  in  the  primary  winding 
of  the  coil  is  almost  instantly  destroyed  whenever  the  battery  cir- 


FIGS.  196  and  197.— Contact  Breakers  for  Two  and  Four-Cylinder  Engines 
of  the  general  type  resembling  that  shown  in  the  last  figure.  As  may 
be  seen,  the  springs  are  brought  into  contact  with  the  anvils  represent- 
ing the  terminals  of  the  circuit,  as  the  projecting  point  on  the  sleeve 
rotates  so  as  to  engage  each  roller  in  turn.  Such  apparatus  are  used 
in  circuits,  having  no  tremblers  on  the  coils. 

cuit  is  broken.  Thus,  it  is  possible  to  obtain  a  high-speed  rate 
in  alternately  making  and  breaking  the  primary  circuit,  while 
at  the  same  time  maintaining  a  secondary  current  of  sufficient 
potential  to  produce  a  powerful  spark  without  interference  from 
the  self-induced  current  produced  in  the  primary  winding  of  the 
coil.  The  action  of  the  condenser  is  virtually  "a  heaping  up 
of  electrical  pressure  at  the  end  of  the  wire  of  the  primary  circuit, 
to  which  it  is  attached."  This,  discharging  through  the  only  avail- 
able outlet,  sweeps  back  through  the  primary  coil  and  instantly 


2S2 


SELF-FROPELLED    VEHICLES. 


demagnetizes  the  core,  owing  to  the  fact  that  its  flow  is  in  the  re- 
verse direction  to  that  of  the  original  self-induced  current.  This 
effect  is  produced  with  great  rapidity,  and  is  a  potent  factor  in 
rendering  the  De  Dion  system  one  of  the  simplest  by  which  a 
high-tension  current  may  be  generated  for  ignition  purposes. 
Among  the  objections  to  the  system  may  be  mentioned  the  fact 
that  a  large  primary  current  is  required  in  proportion  to  the  use- 
ful work  accomplished,  which  contributes  to  the  end  of  speedily 
exhausting  the  battery. 


FIG.  198.— Ignition  Circuit,  containing  a  Dynamo  Generator  and  Storage 
Battery.  Both,  terminals  of  the  secondary  winding  of  the  induction  coil 
have  visible  leads  to  the  sparking  plug.  An  adjustable  vibrator  on  the 
coil  enables  the  timing  of  the  spark.  As  in  Fig.  329,  the  storage  bat- 
tery furnishes  "current  for  sparking  until  the  dynamo  has  taken  up  its 
speed,  and  may  then  be  cut  out  of  circuit,  as  desired. 

The  Benz  Jump=Spark  Circuit. — .The  constructional  and 
operative  objections  involved  in  the  De  Dion  ignition  circuit  are 
largely  overcome  in  the  Benz,  which  embodies  many  of  the  fea- 
tures most  often  used  with  modern  gasoline  engines  employing 
this  method  of  ignition.  Instead  of  the  notched  cam  and  trembler 
spring  used  on  the  De  Dion,  motor  for  periodically  breaking  the 
cfrcuit,  a  leaf  spring,  carrying  a  contact  button  at  its  free  point, 
bears  against  the  circumference  of  a  rotating  vulcanite  disc, 
which  through  a  small  arc  carries  a  brass  plate  electrically  con- 
nected to  the  spindle  of  the  rotating  disc.  This  spindle  forms 
one  terminal  of  the  induction  coil  primary.  The  spring  bearing 
upon  the  periphery  of  the  rotating  disc  is  connected  direct  to 
the  negative  pole  of  the  battery,  By  this  means,  whenever  th$ 


METHODS  OF  IGNITION. 


283 


brass  plate  on  the  disc  comes  in,  contact  with  the  button  carried  at 
the  extremity  of  the  spring,  the  primary  circuit  is  formed. 

The  induction  coil  used  with  this  ignition  system  is  of  the  usual 
construction,  except  that  it  has  a  magnetically  operated  contact 


FIG.  199.— The  Benz  Jump-Spark  Circuit.  Unlike  the  De  Dion  system  just 
described,  both  the  primary  and  secondary  circuits  are  carried  by  visi- 
ble leads,  no  part  of  either  being  grounded  to  the  frame.  The  circuit 
emerging  from  the  positive  pole  of  the  battery  passes  through  wire,  A, 
to  binding  post,  A'  on  the  coil,  to  one  contact  at  B  of  the  trembler,  C, 
thence  through  C  and  D  to  the  primary  winding  of  the  coil;  then 
through  a  and  d  through  the  condenser,  Q.  The  other  terminal  of  the 
primary  winding  emerges  from  binding  post,  E',  passing  over  lead  wire, 
E,  to  sleeve,  M,  of  the  rotary  cam,  G.  The  sleeve,  M,  is  in  electrical 
contact  with  the  metallic  section,  H,  on  the  circumference  of  the  cam. 
being  turned  on  the  spindle,  F,  so  as  to  periodically  make  contact  with 
the  head,  K,  of  the  trembler  spring,  L.  The  secondary  circuit  is  com- 
pleted through  lead  wires,  R  and  S,  to  the  two  terminals  of  the  plug,  T. 

breaker,  which  serves  to  break  the  primary  circuit  as  soon  as 
the  core  has  acquired  its  full  magnetic  properties.  The  current, 
emerging  from  the  positive  pole  of  the  battery,  moves  along  wire, 
4j  to  binding-post,  Alt  and  thence  to  the  sgrew  B,  which  is  nor- 


284 


SELF-PROPELLED    VEHICLES. 


mally  in  contact  with  spring,  C,  of  the  contact  breaker.  Moving 
through  the  spring,  it  emerges  on  wire,  D,  thence  through  the 
primary  winding  of  the  induction  coil  to  binding-post,  H1,  and 
wire,  E,  which  is  in  electrical  contact  with  the  spindle,  F,  of  the 
rotating  disc,  G.  The  circuit  is  closed,  as  already  stated,  when- 
ever the  brass  arc,  H,  on  the  periphery  of  the  disc  is  brought  into 
contact  with  the  button,  K,  carried  on  the  spring,  L.  The  point 
of  ignition  may  be  timed  by  modifying  the  relative  positions  of 
the  contact  piece,  H,  and  the  button,  K;  this  act  being  accom- 
plished by  loosening  the  adjustment  screw  and  turning  the  disc, 


FIG.  200.— Type  of  French  Wire-Contact  Circuit  Interrupter  used  on  Cir- 
cuits having  Magnetic  Tremblers  on  the  Coils.  As  shown,  the  roller 
comes  into  contact  with  the  arc-shaped  plates  representing  terminals 
of  each  of  the  four  coil  and  plug  circuits,  making  each  of  th  jm  in  suc- 
cession. 

G,  on  the  spindle,  F,  to  the  required  point.  The  metal  sleeve,  M , 
in  contact  with  the  spindle,  F,  maintains  the  electrical  contact  be- 
tween, H  and  F,  and  thus  with  the  wire,  H,  no  matter  what  may 
be  the  degree  at  which  the  contact,  H ,  is  shifted.  The  spindle, 
F,  being  a  secondary  shaft,  rotates  so  long  as  the  engine  is  in 
motion,  thus  making  the  primary  circuit  once  in  every  two  revo- 
lutions of  the  flywheel. 

The  two  terminals,  B  and  C,  of  the  wires,  A  and  D,  are  con- 
nected as  shown  by  the  wires,  a  and.d,  with  the  condenser,  Q, 


METHODS  OF  IGNITION. 


285 


the  object  being,  as  with  the  De  Dion  system,  "to  suppress  the 
spark  discharge  of  the  primary  self-induced  current,  which  other- 
wise would  take  place  on  the  break  of  circuit,  and  to  increase 
the  rate  of  demagnetization  of  the  core." 

As  may  be  readily  understood,  the  primary  circuit  has  scarcely 
been  made  before  the  iron  head  of  the  contact  breaker,  carried 
on  the  spring,  C,  is  attracted  to  the  core  of  the  induction  coil, 
thus  momentarily  stopping  the  flow  of  current.  Its  vibrations, 
however,  are  of  great  rapidity,  averaging  at  least  four  complete 
breaks  during  the  brief  period  in  which  the  brass  piece,  H,  on 
disc,  G,  and  the  button,  K,  on  spring,  L,  are  in  contact.  The  re- 


FIGS.  201  and  202.— The  Rotating  Insulated  Disc  and  Spring  Commutator 
of  the  Locomobile  Gasoline  Engine.  The  rotating  wipe  contact  of  the 
Peerless  engine.  Each  of  the  four  cylinders  is  ignited  in  succession 
as  the  contact  is  made  by  the  rotating  grounded  member.  Tremblers 
used  on  the  coils. 

suit  of  these  rapid  fluctuations  of  the  magnetic  field  is  a  con- 
tinuous stream  of  hot,  flaming  sparks  between  the  points  of  the 
plug,  during  the  period  in  which  the  primary  circuit  is  made,  the 
number  of  impulses  of  the  secondary  current  on  the  wires,  R  and 
$,  to  the  two  terminals  of  the  sparking  plug,  T,  being  greatly  in- 
creased. 


Timing  the  Spark. — With  neither  of  the  systems  as  described 
is  there  any  provision,  except  adjusting  the  cam,  for  advancing 
or  retarding  the  time  of  the  spark — which  is  to  say,  making  the 
closure  of  the  primary  circuit  at  a  point  shortly  before  or  shortly 


286 


SELF-PROPELLED   VEHICLES. 


METHODS  OF  IGNITION. 


287 


after  the  completion  of  the  compression  stroke.  By  advancing 
the  spark  a  longer  period  of  expansion,  consequently  a  greater 
economy  of  effective  power,  is  obtained :  by  retarding  it  the  ex- 
pansion is  shortened,  and  the  power  effect  is  not  as  great.  The 
best  efficiency  is  obtained  when  the  piston  moves  outward  under 
full  power  impulse  from  the  very  start,  which  is  possible  when 
the  gas  mixture  is  in  a  state  of  complete  ignition. 

The  control  of  the  spark  could  be  constantly  in  the  driver's 
hand  with  such  motors  as  have  been  just  described,  if  the  cam 
or  the  commutator  were  set  on  a  sleeve,  arranged,  as  in  the 


FIG.  205.— Steering-  Wheel  and  Attachments  of  the  Pope-Toledo  Carriage.  A 
is  the  wheel  rim;  B,  a  spoke  or  arm  of  the  three-armed  spider;  C,  sector 
for  sliding  arms,  D  and  E;  D,  throttling  arm  and  handle;  E,  spark  reg- 
ulating handle. 

Simms  system,  to  be  shifted  around  through  part  of  a  revolution, 
thus  making  the  spark  occur  at  an  earlier  or  a  later  moment,  or  if 
the  base  holding  the  binding  screws  and  contact  spring  were  ar- 
ranged to  move  through  a  short  arc  around  the  secondary  shaft. 
Such  an  arrangement  has  actually  been  applied  on  a  single  cylin- 
der bicycle  motor,  with  which  a  snap  cam  contact  breaker  is  used. 
With  multiple  cylinder  engines  very  similar  devices  are  used, 
for  periodically  making  the  circuit.  With  many  of  the  best  makes 
of  carriage  the  coil  is  furnished  with  a  magnetic  trembler  and  the 
primary  circuit  is  made  and  broken  by  a  rotating  wipe  contact 


1>SS 


SELF-PROPELLED    VEHICLES. 


commutator.  As  shown  in  accompanying  figures,  the  rotating 
member  may  be  either  an  insulated  disc  with  a  single  conducting 
contact,  as  in  the  Benz  jump-spark  circuit,  or  a  contact  piece 
bearing  on  an  internal  insulated  track  with  conducting  surfaces 
corresponding  to  the  number  of  cylinders  to  the  fired  and  to  the 


FIG.    206.— The    Searchmont    Steering    Wheel    with    Electric    Circuit    Breaker 
One   terminal   is  at   C,   the   other   at   pin,    B.      By   depressing   button,   A 
contact    may    be   broken.      By    withdrawing-   pin,    B,    circuit    may    be    in 
terrupted,  rendering  it  impossible  to  start  the  engine. 

disposition  of  their  cranks  in  degrees.  With  such  devices  the 
spark  may  be  timed,  either  by  turning  the  frame  through  part 
of  a  revolution,  or  by  turning  the  sleeve  carrying  the  rotating 
member.  Precisely  similar  apparatus  are  made  to  operate  with 
snap  cams,  as  shown  in  the  figures.  Several  carriage  motors  have 


FIG.  207.— Steering  Wheel  and  Attachments  of  the  Panhard-Levassor  Car- 
riage. A,  a  shaft  on  a  diameter  of  the  wheel;  B,  a  cylindrical  fixed  cap 
with  toothed  ends:  C,  C.  a  sleeve  with  toothed  ends,  F,  F,  in  normal 
engagement  with  B,  under  tension  of  springs,  E,  E,  being  prevented 
from  rotating;  G,  G,  drums  on  which  wire  cables,  H,  H,  are  secured 
and  wound;  K,  K,  knurled  handles,  which  may  be  grasped  and  pulled 
against  the  springs,  allowing  rotation  of  G,  G.  One  cable,  H,  leads  to 
carburetter  link,  the  other  to  the  spark  adjuster. 

the  spark  timed  by  automatic  action,  as  shown  in  the  cut  of  the 
Riker-Locomobile  governor  in  a  later  chapter.  With  others  it 
is  done  solely  by  the  action  of  the  driver.  Although,  of  course, 
in  every  case,  the  advance  or  retardation  can  extend  through  a 
very  limited  arc,  strictly  within  the  limits  of  safe  firing. 


METHODS  OF  IGNITION. 


289 


The  Outside  Spark=Gap. — By  a  form  of  device  recently  in- 
troduced, the  short-circuiting,  due  to  fouling  and  carbonizing 
deposits  between  the  points  of  a  high-tension  spark  plug,  is 
effectually  overcome.  Since  fully  60  per  cent,  of  motor  troubles 
with  this  variety  of  spark  arise  from  short  circuiting,  the  value 
:of  the  device  must  be  apparent,  and  it  is  fairly  evident  that 
automobile  operation  in  the  future  will  be  a  far  less  troublesome 
pastime  than  was  possible  in  the  past.  Briefly  described,  the 
auxiliary  spark  gap,  as  it  is  called,  is  a  form  of  condenser,  or  ca- 
pacity, in  which  the  air  acts  as  the  dielectric  between  two  sur- 
faces, set  at  the  terminals  of  a  gap  in  a  high  tension  circuit. 


FIG.  208.— Outside    Spark    Gap    in    the    form    of    Chains,    as    applied    on    the 
Riker-Ijocomobile   engine. 

The  conditions  that  enable  the  production  of  a  spark-discharge 
between  the  two  terminals  of  the  gap  in  such  a  circuit  involve 
simply  that  an  electrical  charge  be  accumulated  on  one  terminal 
surface,  until  the  high  pressure  breaks  down  the  dielectrical  re- 
sistance of  the  air,  and  enables  the  spark  to  jump  across.  The 
result  is,  of  course,  that  the  electrical  impulses  are  very  greatly 
intensified,  and  become  capable  of  exerting  many  times  the  effect 
otherwise  to  be  obtained.  This  principle  is  proved  true  in  the 
case  of  high-tension  spark  plugs,  which,  although  so  befouled 


290  SELF-PROPELLED    VEHICLES. 

and  short-circuited  as  to  miss  sparking  with  a  current  of  ordinary 
pressure,  operate  quite  as  well  as  perfectly  new  and  clean  plugs, 
when  the  outside  gap  is  placed  in%  the  secondary  circuit.  The 
reason  for  this  is  that,  the  pressure  having  been  raised  to  many 
times  the  normal  secondary  voltage,  the  oscillating  current, 
moving  swiftly,  is  able  to  arc  across  between  the  metal  points, 
avoiding  the  high-resistance  path  through  the  short-circuiting 
deposit  of  carbon  and  oil  residuum,  in  precisely  the  same  fashion 
that  lightning  leaps  to  a  conductor.  Interesting  experiments 
have  been  tried  to  demonstrate  the  ability  of  an  outside  spark- 
gap  to  produce  a  spark  in  the  motor  cylinder,  even  when  it  was 
impossible  to  use  the  plug  without  it,  and  even  when  an  excess 


FIG.   209.— One    form    of    Outside    Spark    Gap. 

of  lubricating  oil,  deliberately  poured  into  the  combustion  cham- 
ber, quickly  produced  fouling  between  the  points. 

Operative  Advantages  of  the  Spark=Gap. — Other  advan- 
tages of  the  spark-gap  are  that  it  furnishes  a  sure  indication  of 
the  conditions  of  operation — always  sparkling  when  the  plug 
sparks  within  the  cylinder,  and  failing  to  spark  when  any  dis- 
arrangement in  the  outside  circuit  has  interrupted  the  operation 
of  the  battery.  The  time  of  the  spark  may  also  be  accurately 
determined  and  regulated  to  suit  requirements ;  the  fact  of  its 
adjustment  being  always  surely  indicated  to  the  eye.  It  further 
allows  the  secondary  current  to  reach  its  full  tension,  by  elimin- 
ating the  leak  formed  by  the  deposit  of  soot  between  the  terminal 
points  of  the  plug.  As  a  consequence,  also,  the  movement  of  the 
vibrator  on  the  spark  coil  becomes  noticeably  slower,  greatly 
to  the  advantage  of  the  batterv,  whose  life,  according  to  some 
authorities,  is  even  doubled.  This  result  follows,  since  the  ac- 


METHODS  OF  IGNITION. 


291 


cumulations  of  energy  periodically  taking  place  at  the  terminals 
of  the  gap  allow  sufficient  time  for  more  complete  magnetizations 
and  demagnetizations  of  the  core,  with  the  result  that  the  primary 
current  reaches  its  maximum  more  slowly — the  secondary  being 
unable  to  discharge  with  the  same  rapidity  as  when  no  gap  is 
used.  According  to  the  claims  of  some  authorities,  it  is  possible 
with  the  use  of  a  well-designed  spark-gap  to  spark  successfully, 


FIG.  210.— The  King  Automatic  Spark-timing  Device.  It  consists  essentially 
of  a  rotating  member,  deriving  its  movement  from  the  secondary  shaft 
of  the  engine,  and  automatically  regulated  with  relation  to  the  four 
spark  plug  terminals  by  a  spring  governor  mechanism.  Between  this 
rotating  member  and  each  terminal  is  a  gap,  an  auxiliary  spark  gap. 
A,  B,  C,  D,  are  the  plugs;  E,  the  primary  and  secondary  lead  from  the 
single  coil  grounded  to  the  engine  at  H;  F,  the  secondary  positive  lead; 
G,  the  primary  positive  lead. 

even  with  faulty  insulation  in  the  secondary  circuit,  such  as  would 
entirely  prevent  ignition  under  ordinary  circumstances. 


Design  and  Adjustment  of  Spark=Gaps. — Among  the  im- 
portant points  touching  the  design  and  operation  of  spark-gaps 
may  be  mentioned  those  concerning  the  distance  apart  of  the 
charging  points,  the  shape  of  the  points,  and  on  the  question  of 
maintaining  the  resistance  of  the  air-dielectric.  The  space  be- 
tween the  sparking  points  varies  between  1-32  inch  and  ^  inch, 


292  SELF-PROPELLED    VEHICLES. 

according  to  the  requirements  in  hand,  which  can  often  be  best 
determined  by  experiment  and  adjustment.  As  a  general  rule, 
the  further  apart  the  points  are  fixed — of  course,  within  the 
limits  named — the  better  the  effect ;  since,  by  thus  obtaining  a 
higher  resistance  in  the  intervening  dielectric,  the  pressure  in  the 
secondary  circuit  is  enabled  to  rise  to  its  maximum  strength, 
before  a  discharge  can  occur.  The  result  is  a  spark  of  far  higher 
calorific  value.  According  to  general  directions  furnished  by 
manufacturers,  the  adjustment  "of  distance  between  the  points 
of  a  spark-gap  should  be  made  while  the  engine  is  in  operation. 
The  best  results  may,  then,  be  accurately  determined. 

In  addition  to  obtaining  a  sufficient  distance  between  the  point 
to  secure  the  required  dielectric  resistance,  some  authorities  claim 
that  air  shoiuld  be  allowed  to  circulate  freely  in  the  instrument, 
thus  preventing  the  lowering  of  resistance  due  to  heating.  This, 
however,  seems  to  be  contrary  to  the  practice  followed  in  some  of 
the  most  successful  types  of  the  apparatus,  which  are  made  with  a 
case  enclosing  the  points  quite  completely,  and  providing  a  glass 
top  for  the  purpose  of  enabling  observation  by  the  driver.  With 
Y%  inch  space  between  the  points  the  resistance  of  the  air  seems 
to  be  sufficient  under  all  conditions  for  the  common  requirement 
of  most  motors. 

The  Shape  of  the  Gap  Terminals.  — Many  makers  of  these 
instruments  point  the  terminals,  others  claim  that  this  is  an  error, 
since  points  allow  the  current  to  slip  over  the  air  gap  in  a  fine 
brushlike  stream,  thus  effectively  lowering  the  voltage,  and  inter- 
fering with  the  prime  requirement  in  the  gap,  "to  dam  up  the 
current  until  there  is  a  sufficiently  large  pressure  stored  at  the 
terminal  to  overcome  the  dielectric  resistance,  and  jump  across  in 
a  lump."  While  pointed  terminals  operate  moderately  well,  par- 
ticularly when  a  sufficient  gap  is  arranged  between  them,  the 
criticism  here  made  is  supported  by  the  common  practice  in 
other  branches  of  electrical  industry,  in  which  high-tension  sparks 
are  used — ball  terminals  being  the  nearly  invariable  rule.  In 
the  new  Riker  gasoline  cars  the  spark  gap  takes  the  form  of  a 
chain,  which  also  serves  as  a  flexible  attachment  for  the  con- 
ductors. The  sparks  leap  across  such  gaps  as  occur  between 
the  links,  thus  apparently  accomplishing  quite  as  good  security 
for  perfect  plug  operation,  as  found  with  other  types. 


METHODS  OF  IGNITION. 


293 


Wiring  a  Spark=Gap.— In  wiring  the  spark-gap  it  is  neces- 
sary only  to  open  the  secondary  circuit  and  insert  the  device. 
If  it  is  to  be  mounted  on  the  dash  board,  heavily  insulated  cable 
must  be  used,  as  the  high  tension  current  is  liable  to  short- 
circuit  with  ordinary  bell-wire  coverings.  In  general,  long 
reaches  of  wire  should  be  avoided  as  much  as  possible,  and,  if 
used,  should  be  of  low  resistance.  Occasionally,  in  such  cases 
it  is  necessary  to  use  some  form  of  compensator. 

1 


FIG.  211  —"American"  Indestructible  Sparking  Plug.  This  plug  has  two 
essential  parts— the  shell  carrying  one.  electrode,  which  screws  into  the 
metal  of  the  cylinder,  and  the  core  cerfcjposed  of  mica,  through  which 
runs  the  other  terminal,  the  two  being  jpined  together  by  screw  con- 
nections as  shown.  The  superior  advantages  of  mica  insulation,  as 
claimed  by  the  manufacturers,  are  that  heat  has  no  effect  whatever 
upon  it;  thus  rendering  it  much  more  durable  than  a  plug  made  of 
porcelain  or  other  substance  liable  to  be  affected  by  heat  and  allow 
short-circuiting  of  the  sparking  current. 


FIG.  212.— Part  Sectional  View  of  the  Mezger  Porcelain  Spark  Plug.  Like 
the  plug  just  shown,  the  shell  of  the  plug  is  in  two  parts— one  screwing 
into  the  wall  of  the  cylinder,  the  other  into  the  first.  The  porcelain 
insulating  core  is  held  between  them  by  a  shoulder.  The  insulated  elec- 
trode rod  is  let  through  a  perforation  in  the  porcelain,  having  a  shoulder 
to  bear  against  it  at  one  end,  as  seen,  and  being  threaded  to  receive  a 
retaining  nut  at  the  other.  Ample  air  spaces  are  shown  between  the 
porcelain  and  the  two  terminals  of  the  circuit. 

Points  on  Sparking  Plugs. — As  previously  stated,  the  plugs 
used  for  sparking  on  high-tension  circuits  consist  essentially  of 
two  terminal  electrodes  separated  by  an  air  gap  of  such  length  as 
to  permit  a  spark  to  arc  across  at  the  given  tension  of  the  sec- 
ondary circuit.  These  two  electrodes  must  be  in  contact  at  no 
other  point,  nor,  if  we  are  to  have  a  spark  sufficient  to  ignite  the 
fuel  charge  in  cylinder  must  the  insulation  be  imperfect  at  any 


SELF-PROPELLED    VEHICLES. 


point  along  the  leads,  so  as  to  admit  of  short-circuiting  or  leaking. 
From  a  theoretical  point  of  view  the  problem  is  a  simple  one, 
since  there  are  many  dielectrics  whose  resistance  is  so  immense 
as  to  render  them  very  nearly  absolute  insulators.  Practically, 


FIG.  217. 


FIG.  218. 


FIG.  218a. 


FIG.  2181). 


FIGS.  213-218.— Sections    of    Well-known    Spark    Plugs.      The    first    six    have 
porcelain  insulation;  the  last  two,  mica. 

however,  there  are  a  number  of  considerations  that  enter  to  render 
the  construction  and  operation  of  sparking  plugs  a  matter  by  no 
means  simple.  In  the  first  place,  the  very  high  temperature  with- 
in the  combustion  space  of  a  gas  engine  is  liable  to  so  affect  many 


METHODS  OF  IGNITION.  295 

substances  that  might  be  used,  so  as  to  destroy  the  insulation. 
In  the  second  place,  the  constant  splashing  of  the  lubricating  oil 
quickly  befouls  the  plug,  and  the  oil  being  burned  and  carbonized 
in  the  heat  of  combustion  produces  a  deposit  that  allows  the  cur- 
rent to  travel  across  the  gap  without  sparking,  thus  destroying 
the  efficiency  of  the  plug  until  cleansed.  Furthermore,  if  the  in- 
sulating substance  is  cracked  or  soaked  in  oil,  the  short  circuit 
occurs  at  some  point  short  of  the  spark  gap,  involving  that  the 
plug  must  be  replaced.  Although,  as  already  explaine .,  the  out- 
side spark  gap  is  highly  efficient  in  overcoming  very  many  spark 
plug  troubles,  it  stands  to  reason  that  such  as  involve  a  breaking 
down  of  the  insulation  must  be  otherwise  remedied. 


FIG.  219.— Double  Spark  Plug  used  on  the  Cadillac  Carriage.  Unlike  other 
plugs,  the  secondary  circuit  is  carried  by  visible  leads,  and  is  not 
grounded  at  any  point.  Superior  sparking  qualities  are  claimed,  and, 
as  seems  evident,  fouling  is  a  more*  remote  danger. 

Spark  Plug  Insulation. — The  substances  most  often  used 
in  insulating  spark  plugs  are  porcelain  and  mica.  The  porcelain, 
as  shown  in  the  accompanying  sectional  views  of  typical  plugs, 
is  molded  into  the  shape  deemed  most  desirable  by  the  designer 
and  is  pierced  from  end  to  end  to  admit  the  spindle  of  the  positive 
electrode.  Porcelain  is  well  suited  for  the  purpose  of  spark-plug 
insulation,  since  it  possesses  very  high  resistance  both  to  heat  and 
to  the  electric  current.  In  fact,  a  high  quality  of  porcelain  should 
not  break  down  with  either  the  heat  or  the  electrical  tension  en- 
countered in  gas  engine  operation.  That  porcelains  are  broken 
under  such  conditions  is  due  to  uneven  heating  of  the  insulating 
tube  or  to  some  unexpected  violence.  Its  brittleness  is  nearly  the 
worst  objection  to  its  use,  Lower  qualities  of  porcelain  are,  of 


296  SELF-PROPELLED    VEHICLES. 

course,  much  more  easily  broken,  and  thereby  produce  short-cir- 
cuiting under  ordinary  conditions  of  temperature  and  electrical 
tension.  Mica,  a  substance  possessing  an  electrical  resistance  of 
84,ooo,(XX),ooo,(X)O  ohms  per  cubic  centimeter  is  an  ideal  insul- 
ator, except  for  the  fact  that  it  frequently  contains  impurities  that 
reduce  its  dielectric  efficiency,  and  also  because,  owing  to  its  lami- 
nated structure,  oil  and  gas  may  be  forced  by  the  pressure  of 
compression  between  the  sheets  composing  the  insulating  sheath, 
thus,  in  time  producing  short-circuiting  of  the  current.  In  order 
to  obviate  this  trouble,  one  manufacturer,  whose  plug  is  shown 
among  the  sections,  adopts  the  plan  of  tapering  both  the  electrode 
spindle  and  the  mica  sheath  around  it,  thus,  as  is  claimed,  pro- 
ducing a  perfectly  gas-tight  joint,  and,  instead  of  allowing  gas  to 
be  forced  between  the  laminae,  providing  for  an  increasing  tight- 
ness of  contact  as  the  metal  of  the  spindle  expands  with  heat. 

"Mica  cores,  built  up  of  thin  disks  of  sheet  mica,  even  if  care- 
fully selected,  are  seldom  free  from  iron,  and  the  sheet  mica  can- 
not be  so  closely  united  as  to  entirely  prevent  a  deposit  of  fine 
particles  of  carbon  being  pressed  between  the  layers  by  the  force 
of  the  explosions,  thus  rendering  the  insulation  imperfect.  This 
causes  misfiring,  and  as  the  offending  plug  is  to  all  appearances 
perfect,  it  often  occasions  the  operator  much  annoyance. 

"These  remarks  also  apply  to  other  substances,  such  as  lava  or 
artificial  stone,  which,  being  porous,  are  imperfect  insulators." 

Structural  Points. — Practically  all  spark  plugs  of  later  pat- 
terns are  made  with  an  air-space  at  the  end  between  one  of  the 
electrodes  and  the  insulating  core,  in  order  to  give  opportunity 
for  a  "vortex"  of  air  and  gas  to  expel  carbon  deposits,  as  the 
charge  is  alternately  compressed  and  expanded.  Most  mica- 
insulated  plugs  having  the  inner  spindle  sheathed  with  concentric 
coats  of  mica  have  also  a  cap  at  the  end  of  the  sheath  to  protect 
it  and  to  ensure  the  attachment  of  the  spindle.  Many  plugs  using 
porcelain  insulation  have  the  porcelain  in  two  or  more  parts,  so 
as  to  avoid  the  troubles  arising  from  uneven  temperatures. 


CHAPTER    TWENTY-TWO. 

THE  DEVELOPMENT  OF  THE  GASOLINE  MOTOR  VEHICLE  BY 
GOTTLIEB  DAIMLER  AND  HIS  SUCCESSORS. 

Daimler's  Contributions  to  Explosive  Motor  Construction. — 

The  use  of  explosive  motors  for  propelling  road  vehicles  was 
made  possible  by  the  inventions  of  Daimler,  after  whose  designs 
practically  all  vehicle  motors  are  constructed  to  the  present  day. 
The  improvements  introduced  by  him  were  principally  those 
that  made  it  possible  to  use  a  mineral  spirit  or  liquid  fuel,  and 
the  attainment  of  a  higher  speed  than  was  possible  with  the 
older  engines  of  the  Otto  type.  With  increased  speed,  a  lighter 
weight  and  smaller  proportions  were  made  possible.  The  Otto 
engines  in  use  until  the  date  of  his  memorable  inventions  could 
attain  only  a  very  slow  speed,  both  on  account  of  the  compli- 
cated and  uncertain  slide  valve  arrangements  and  also  from  the 
system  of  igniting  the  charge  by  the  constantly  burning  gas  jet 
and  slide.  Daimler  struck  at  the  root  of  the  difficulties  and  con- 
structed his  earliest  types  of  engine  with  the  poppet  valves,  now 
in  universal  use,  and  with  the  familiar  hot-tube  ignition.  This 
latter  contrivance  alone  was  largely  instrumental  in  attaining 
the  end  of  high  speed,  since,  as  already  described,  ignition  is 
directly  due  to  forcing  of  fuel  mixture  into  the  incandescent 
tube  by  the  pressure  of  compression.  This  method  of  contact 
was,  of  course,  impossible  with  the  flame  and  slide  ignition,  as 
was  also  any  very  high  degree  of  compression.  Consequently, 
only  the  lowest  speeds  were  attainable  with  the  older  Otto  en- 
gines. Daimler,  furthermore,  constructed  his  cylinders  with  a 
stroke  long  in  proportion  to  the  total  content,  thus  permitting 
such  high  compressions  that  the  heat  of  the  cylinder  walls  was 
sufficient  to  produce  ignition  of  the  charge,  after  the  first  few 
strokes  ignited  by  the  hot  tube,  or  "priming-cap,"  as  he  called  it. 

Daimler  Valve  Governors. — The  inlet  valves  of  the  early 
forms  of  Daimler  engine  were  operated  by  atmospheric  press- 
ure acting  against  a  vacuum  created  by  the  out-stroke  of  the 
piston,  as  in  all  gasoline  cylinders  of  the  present  day.  His  ex- 

297 


298 


SELF-PROPELLED    VEHICLES. 


haust  valves  were  positively  operated  with  the  familiar  cam- 
actuated  push-rod,  although  the  cam  mechanism,  instead  of  work- 
ing on  a  secondary  shaft,  as  at  present,  consisted  of  two  eccentric 
grooves  on  the  face  of  one  of  the  inclosed  fly-wheels,  in  which 
traveled  a  feather  at  the  end  of  the  valve  rod. 

By  means    of    a    switch  operated  by  a  simple  governor,  the 


FTG.  220.—  Diagram  of  the  earliest  Daimler  Gasoline  Motor;  used  on  Daimler's  first 
bicycle.  The  parts  are  indicated  by  numbers  as  follows:  17  is  the  driving  belt 
passing  around  the  pulley  on  the  main  shaft  and  tightened  by  jockey  pulley,  19,  and 
link,  21.  31  is  a  rotary  fan,  consisting  of  a  number  of  radial  lins  as  shown,  which 
keeps  a  current  of  air  passing  through  the  air  jacket,  33.  34  is  the  cylinder  shown  in 
part  section. 

feather  running  in  the  cam  groove  could  be  shunted  from  its 
regular  coujse,  so  as  to  run  in  a  nearly  circular  path,  thus  giving 
no  motion  to  the  exhaust  valve,  and  keeping  it  closed.  So  soon, 
however,  as  the  speed  began  to  fall  to  the  normal,  the  governor 
again  shifted  the  switch,  with  the  result  of  again  resuming  the 
operation  of  the  valve,  and  exhausting  the  burned-out  gases  con- 


GASOLINE  VEHICLE  DEVELOPMENT.  399 

tained  within  the  cylinder.  The  shunting  governor  was  speedily 
replaced  by  another  form  of  valve-controlling  device,  in  which  a 
centrifugal  ball  governor  on  the  main  shaft  was  arranged  to  move 
a  sliding  sleeve  outward  and  actuate  an  upright  lever.  The  upper 


FIG.  221.— Part  sectional  view  of  the  Daimler  V-shaped  Gasoline  Engine,  showing  the  air 
valve  in  the  piston  and  eccentric  cam  grooves  on  the  fly-wheel  disc.  The  method  of 
opening  the  exhaust  valve  is  also  indicated. 

arm  of  this  lever,  moving  inward  toward  the  cylinder,  deflected 
the  push-rod  working  in  the  cam  grooves,  so  as  to  make  it  miss 
the  end  of  the  valve  rod,  thus  causing  the  valve  to  remain  closed 
until  the  speed  again  falls  to  normal.  A  governing  device  of 
this  description  is  shown  in  an  accompanying  figure. 


300 


SELF-PROPELLED   VEHICLES. 


The  piston  Air  Valve  of  the  Daimler  Engine. — Another 
feature  of  the  earlier  Daimler  engines  was  the  supplementary 
air  valve  in  the  piston,  the  location  and  general  construction  of 


:'  • 


FIG.  222.— The  Daimler  V-shaped  Gasoline  Engine,  witn  carburetter  and  parts  attached. 
The  object  of  constructing  an  engine  with  cylinders  arranged  as  shown  is  to  double 
the  p  iwer  capacity  without  correspondingly  increasing  the  weight.  This  style  of 
motor  has  been  practically  abandoned,  arid  is  no  longer  manufactured  by  the 
Daimler  Companies. 

which  is  shown  in  the  half-sectional  view  of  the  V-shaped,  engine. 
The  object  was  to  compensate  the  imperfect  operation  of  the  sur- 
face curburetters  used  with  these  engines,  and  secure  the  in- 


GASOLINE  MOTOR  DEVELOPMENT.  301 

jection  of  a  sufficient  additional  quantity  of  air  to  secure  the 
combustion  of  the  charge.  The  operation  of  this  valve  involved 
that  the  crank  chamber  should  serve  as  a  reservoir  for  air  ad- 
mitted through  a  valve  in  its  wall  under  suction  of  the  piston 
during  its  in-stroke.  On  the  out-stroke  of  the  piston  which 
draws  in  the  fuel  mixture  through  the  inlet  valves,  the  piston  air 
valve  is  caused  to  open,  by  the  superior  pressure  of  the  air  in  the 
crank  chamber  and  in  front  of  the  piston.  As  shown  in  the  half- 
sectional  drawing  of  the  V-shaped  engine,  the  valve  spring  bears 
at  one  end  against  the  inside  end  wall  of  the  trunk  piston  and 
at  the  other  against  a  shoulder  sliding  on  the  valve  stem.  On 
the  out-stroke,  accordingly,  this  shoulder  comes  into  contact 
with  the  fork  shown  on  an  upward  inside  projection  from  the 
lower  end  of  the  cylinder,  being  forced  upward  and  compressing 
the  spring  against  the  upper  wall  of  the  piston.  The  valve  rod, 
being  thus  relieved  from  spring  pressure,  is  free  to  rise  in  obedi- 
ence to  the  superior  pressure  of  the  air  within  the  crank  case, 
which  is  forced  in  as  the  fuel  charge  enters  from  the  opposite 
end.  During  the  firing  stroke  the  spring  is  similarly  compressed, 
although,,  owing  to  the  greater  pressure  of  the  expanding  gases 
behind  the  piston,  the  valve  is  held  in  its  seat.  This  piston  valve 
was  used  on  Daimler  engines  for  only  a  few  years,  its  function 
being  afterward  discharged  much  more  satisfactorily  by  adjust- 
able air  inlet  valves  in  connection  with  the  carburetter. 

The  object  sought  in  the  V-shaped  engine  was  to  secure  an  up- 
right construction,  with  the  full  effect  of  two  cylinders  operating 
on  the  same  crank,  thus  saving  both  space  and  weight,  in  a 
manner  impossible  with  opposed  cylinders  of  long  stroke. 

Water  Cooling  and  Ignition  Devices. — In  the  early  engines 
of  the  Daimler  pattern  the  cylinder  cooling  was  accomplished 
by  means  of  a  rotary  fan  worked  on  the  crank  shaft  of  the  engine, 
and  forcing  the  air  through  a  form  of  jacket  surrounding  the 
entire  upper  portion  of  the  cylinder.  The  floats  of  this  fan  are 
shown  at  the  points  marked  31  in  an  accompanying  illustration, 
and  the  jacket  at  33.  By  this  device  a  constant  current  of  cold  air 
was  forced  against  and  around  the  cylinder.  Of  course,  the  later 
Daimler  motors,  designed  for  vehicle  use,  have  the  ordinary 
water-jacket  cooling  system,  any  form  of  air-cooling  being  evi- 
dently inadequate  to  the  demands  of  even  average  traffic. 


302 


SELF-PROPELLED  VEHICLES. 


The  hot-tube  ignition  is  still  used  by  the  Daimler  companies 
of  Germany,  England  and  America,  as  also  by  several  of  the 
French  motor-carriage  builders  using  the  Daimler  engines.  This 
system  is  successful  on  account  of  the  long  stroke,  characteristic 
of  the  Daimler  cylinder,  which  gives  a  correspondingly  high 
compression  ratio,  involving  certain  and  efficient  ignition  of  the 
charge  at  high  speeds.  However,  certain  European  automobiles, 
such  as  the  Mercedes-Daimler,  have  latterly  been  constructed 
with  the  primary  circuit  break-contact  system,  with  current 


FIG.  223.— One  type  of  Gas  Engine  Governor,  which  is  an  improved  varia- 
tion of  the  device  used  on  the  early  Daimler  motors.  The  parts  are  as 
follows:  A  and  A,  ball  weights;  B  and  B,  bell  cranks  actuating  the 
links,  C  and  C,  as  the  balls  move  outward  resisting  the  tension  of 
spring,  S,  and  sliding  sleeve,  D,  on  the  shaft,  M.  E  is  a  lever  arm 
attached  to  D,  which  moves  the  shaft,  G,  by  contact  at  F,  as  shown, 
thus  throwing  the  pick  blade,  H,  out  of  contact  with  the  end,  J,  of  the 
exhaust  valve  rod. 

supplied  by  magneto-generators.     Some  of  the  later  Panhards 
are  equipped  with  the  jump-spark  ignition. 

Motors  and  Motor  Design. — While  an  account  of  the  motors 
used  on  gasoline  automobiles  must  be  historical,  as  well  as  de- 
scriptive, it  would  be  frivolous  to  attempt  describing  all  the 
typical  forms  that  have  been  produced,  or  even  to  notice  the 


GASOLINE  MOTOR  DEVELOPMENT. 


303 


greater  proportion  of  those  most  conspicuous  for  success.  Such 
a  procedure  would  unnecessarily  add  to  the  size  of  this  book, 
and  at  the  same  time  thwart  the  end  for  which  it  is  written — 
to  give  the  reader  a  good  idea  of  the  constructive  and  operative 
principles  involved. 


FIG.  224.— Governor  Mechanism  of  the  later  Daimler  Motors.  As  showii 
in  this  cut,  the  cam,  A,  bearing  upon  the  roller,  C,  lifts  the  arm,  D, 
pivoted  at  K,  and  held  in  position  by  a  spring,  J.  By  lifting  arm,  D, 
it  also  lifts  pushrod,  B,  which  opens  the  exhaust  valve.  When,  how- 
ever, the  speed  of  the  motor  has  increased  beyond  the  predetermined 
limit  a  sleeve  of  varying  diameter,  sliding  on  the  same  shaft,  L,  to 
which  the  cam,  A,  is  fixed,  is  moved  so  that  the  larger  diameter  is 
brought  to  bear  against  the  downward  extension,  H,  of  the  arm,  F, 
thus  causing  F  to  incline  on  the  pivot,  K,  toward  the  cylinder  (at  the 
right  as  in  the  cut),  hence  pushing  rod,  B,  by  link,  E,  out  of  range  of 
arm,  D,  as  it  is  moved  upward  by  impulse  from  cam,  A.  In  this  case 
the  exhaust  valve  is  not  opened  and,  the  products  of  combustion  being 
retained  in  the  cylinder,  there  is  no  feeding  of  fresh  fuel  gas. 

In  general,  all  automobile  motors  correspond  to  one  description 
of  valve-operating  and  gearing.  The  principal  points  of  vari- 
ation touch  such  constructions  as  deal  (i)  with  the  special 
designs  for  increasing  efficiency,  and  (2)  for  enabling  more 


304 


SELF-PROPELLED    VEHICLES. 


complete  control,  either  automatic  or  manual.  Under  the  first 
head  may  be  included  such  elements  of  design  as  refer  to  the 
diameter  of  the  cylinder  bore  and  the  length  of  the  stroke, 
as  compared  to  the  horse-power  rating,  also  to  the  speed  at 
which  the  piston  is  designed  to  travel  when  the  motor  is  yielding 
the  highest  output  of  power.  The  size,  arrangement  and  position 


FIG.  225.— Mechanism  of  the  Peugeot  Variable  Exhaust  Valve  Lift.  A  is  a 
link  attached  to  spool,  J,  sliding  on  the  rotating  shaft,  H,  as  shaft  G 
is  slid  backward  or  forward  according  to  the  impulses  of  the  centri- 
fugal governor.  The  link,  A,  actuates  the  lever,  B,  sliding  the  roller, 
J,  on  shaft,  K.  The  roller,  J,  forming  the  fulcrum  of  lever,  D,  being 
thus  slid  backward  or  forward,  varies  the  lift  of  valve  rod,  C,  as  actu- 
ated by  the  cam,  E,  bearing  upon  the  roller,  F. 


of  the  valves  have  also  been  modified  by  some  designers,  with  a 
view  to  gaining  various  advantages,  such  as  will  be  suggested 
later  on.  Several  well-known  engines  depart  from  the  generally- 
adopted  plan  in  having  the  inlet  valves  positively  operated,  as 
are  to  exhaust  valves ;  but  this  opens  a  question  regarding  which 
authorities  are  by  no  means  agreed. 


GASOLINE   MOTOR    DEVELOPMENT.  305 

In  the  matter  of  governing  the  motor  several  important  con- 
sideratidns  appear,  and  the  designs  still  in  use  differ  on  the  .ques- 
tion whether  regulations  should  consist  in  changing  the  fuel 
mixture,  retarding  the  spark,  or  simply  in  interrupting  the  action 
of  the  exhaust  valve.  That  any  one  of  these  methods  may  be 
effective  seems  to  be  acknowledged.  Several  motors  are  con- 
trolled by  two  such  meajns.  The  question  is  largely  one  of 
economy  of  power  and  simplicity  of  construction. 

Devices  for  Balancing;  Motor  Operation. — Another  problem 
of  considerable  importance  in  the  design  of  a  motor  vehicle  is 
how  to  secure  a  perfectly  balanced  operation  of  the  motor.  This 
is  very  essential,  since  not  only  will  an  unbalanced  movement  of 
the  motor  proceed  a  vibration  that  is  at  once  annoying  to  the 
passengers  and  destructive  to  the  framework  of  the  carriage,  but 
it  also  involves  a  very  great  loss  of  power.  A  single  cylinder 
motor  will  necessarily  cause  considerable  vibration  when  hung 
upon  the  light  frame  of  the  motor  vehicle,  which  can  take  up  and 
transmit  the  vibrations,  due  to  compression  in  the  cylinder,  which 
offers  a  considerable  resistance  to  the  free  rotation  of  the  fly- 
wheel. The  reason  for  this  is  obvious,  for  since  in  the  ordinary 
four-cycle  motor  there  is  one  power  stroke  in  each  two  revolu- 
tions of  the  fly-wheel,  there  is  necessarily  considerable  unevenness 
of  motion.  In  the  Daimler  V-shaped  engine  the  two  pistons  work 
upon  ojne  crank,  the  power  stroke  in  one  cylinder  being  contem- 
poraneous with  the  suction  stroke  in  the  other,  and  the  succeeding 
strokes  of  the  cycles  in  both  being  in  the  same  order.  This  ar- 
rangement secured  a  good  balance  from  the  reason  that  a  power 
impulse  occurred  in  every  revolution  of  the  fly-wheel.  The  V-- 
shaped motor  was  used  on  all  cars  manufactured  by  the  Daimler 
companies  and  by  Panhard-Levassor  and  others  go  for  the  first 
few  years  of  automobile'  history.  This  model  was  then 
abandoned  for  the  parallel  double  cylinder  motor,  as  it  is  known 
to-day.  With  the  earliest  double  cylinder  motors,  however,  the 
two  cranks  were  set  at  180  degrees,  making  the  out-stroke  in  one 
cylinder  simultaneous  with  the  in-stroke  in  the  other.  This 
arrangement  was  adopted  with  the  idea  that  balanced  movement 
and  neutralization  of  vibration  should  be  thus  best  attained.  How- 
ever, in  the  later  Panhard  vehicles  using  double  cylinder  motors 
both  piston  rods  work  on  a  single  crank  pin,  so  that  both  pistons 


306  SELF-PROPELLED    VEHICLES. 

make  in-strokes  and  out-strokes  at  the  same  time,  as  in  the  old 
V-shaped  model.  This  is  the  plan  now  most  usually  adopted 
whenever  only  two  cylinders  are  used.  Four-cylinder  motors 
are  in  this  respect  really  double  two-cylinder  motors — two  of 
the  cylinders  being  always  at  out-stroke,  and  two  at  in-stroke. 


FIG.  226.— The  Phenix-Daimler  Double -vertical -cylinder  Six -horse -power 
Motor,  as  used  by  Panhard-Levassor.  A  is  the  port  for  admitting  fuel 
gas  under  piston  suction;  B,  the  inlet  valve;  B',  the  exhaust  valve;  C, 
the  ignition  apparatus;  D,  spring  on  the  exhaust  valve;  D',  exhaust 
valve  rod;  E,  pushrod  actuated  by  the  cam;  F,  governor  attachment; 
N,  wheel  on  the  cam  shaft,  carrying  the  governor;  R,  the  centrifugal 
weights  of  the  governor;  R',  the  governor  springs;  R",  sliding  ram 
shaft;  S,  the  cam  actuating  the  exhaust  valves;  (2),  the  engine  flywhoel 
carrying  the  female  cone  of  the  main  clutch. 

Another  type  of  motor  very  frequently  employed  where  two 
cylinders  are  used  is  that  known  as  the  double  opposed  cylinder 
type  such  as  is  used  on  the  Haynes-Apperson,  the  Stevens- 
Duryea,  the  Autocar  and  other  American  vehicles.  In  this  type 
the  two  cylinders  are  set  at  opposite  ends  of  the  common  crank 


GASOLINE    MOTOR    DEVELOPMENT. 

chamber,  the  two  piston  rods  working  upon  cranks  set  at  180 
degrees.  This,  of  course,  involves  that  the  cylinders  are  some- 
what offset,  so  that  lines  drawn  through  the  centres  of  each 
would  be  parallel  instead  of  continuous.  As  may  be  readily 
understood,  the  effect  of  two  oppositely-placed  cylinders  working 
upon  cranks  at  180°,  is  the  same  as  that  produced  by  two  upright 
parallel  cylinders  working  on  the  same  crank.  This  is  to  say  the 
two  out-strokes  and  the  two  in-strokes  are  contemporaneous,  the 
firing  stroke  in  one  cylinder  taking  place  at  the  same  time  as 
the  suction  stroke  in  the  other.  Very  few  gasoline  carriages  use 
a  three-cylinder  motor,  the  most  notable  American  example  being 


FIG.  227.— Double  Opposed  Horizontal  Cylinder  Motor  of  the  Haynes-Apper- 
son  Carriages.  The  two  cylinders  of  this  motor  are  somewhat  offset, 
as  shown  in  the  cut,  the  crank  rods  working  on  two  cranks.  The  long 
crank  shaft  shown  at  the  front  of  the  engine  is  for  carrying  the  change 
speed  gear  already  described.  The  reciprocating  parts  are  lubricated 
by  adjustable  oil  feed  cups  shown  at  the  top  of  each  cylinder.  Ignition  is 
by  break  contact  spark,  the  exhaust  connections  being  on  the  same 
plan  as  those  described  for  other  motors.  The  inlet  valves  are  oper- 
ated by  suction,  and  are  at  right  angles  to  the  positively  operated 
exhausts. 

Duryea  carriage,  which  has  three  parallel  cylinders  working  on 
cranks  at  120  degrees.  The  manufacturers  claim  for  this  ar- 
rangement a  higher  degree  of  balance  than  is  attainable  with 
either  two  or  four  cylinders.  Since  only  a  part  of  a  stroke  in  each 
cylinder  is  contemporaneous  with  another  part  of  another  stroke 
in  each  of  the  others,  the  vibration  resulting  from  operation  of 
the  car  is  distributed  throughout  the  cycles  for  the  three  cylinders, 
being  thus  completely  neutralized.  This  result  is  explained  by  the 
theory  that  in  a  multiple  cylinder  motor,  with  properly  disposed 
cranks,  the  vibrations  are  properly  decreased  as  the  square  of 
the  number  of  the  cylinders.  This  would  give  a  three-cylinder 


308  SHIP-PROPELLED    VEHICLES. 

motor  nine  times  less  vibration  than  would  be  possible  with  a 
single  cylinder  motor,  and  as  between  it  and  a  two-cylinder 
motor  the  ratio  would  be  as  9  is  to  4.  We  may,  therefore,  under- 
stand that,  since  the  vibration  of  a  gasoline  motor  is  to  be  at- 
tributed to  the  fact  that  the  power  rotating  the  fly-wheel  acts  but 
once  in  two  revolutions  a  perfect  neutralizing  of  vibration  de- 
mands in  a  multiple-cylinder  motor : 

(1)  That  the  flywheel  should  be  as  heavy  as  possible  for  the 
power  rating  of  the  engine,  and  of  as  large  a  diameter  as  is 
consistent  with  economy  of  space  and  power;  so  as  to  absorb 
as  much  of  the  vibration  as  possible,  while  maintaining  good 
balance  of  movement. 

(2)  The  cranks  should  be  so  set  as  to  distribute  the  stages 
in  the  cycles  of  the  several  cylinders  as  much  as  possible  so  thai 
the  power  impulses  will  be  approximately  continuous,  as  in   a 
steam  engine;  the  continual  successions  of  power  and  no  power 
being  thus  interrupted.    By  this  means  a  greatly  reduced  strain  is 
thrown  upon  the  flywheel  and  the  moving  parts,  with  the  result 
that  the  vibration  and  wear  are  equally  reduced. 

Data  on  Motor  Balancing. — Until  very  recently  the  matter  of 
motor  vibration  has  been  a  serious  consideration-.  Even  with  the 
greatest  care  in  designing  the  trouble  has  not  been  overcome,  and 
motors  running  free  in  some  carriages  have  been  observed  to  pro- 
duce the  most  startling  effects.  On  account  of  such  results  many 
designers,  notably  De  Dion  &  Bouton  of  France,  have  long  been 
known  as  advocates  of  the  single  cylinder,  and  have  actually  been 
very  successful  in  producing  motors  in  which  vibration  is  mini- 
mized. This  result  has  been  achieved  very  largely  by  reducing 
the  length  of  the  stroke  in  proportion  to  the  diameter  of  the 
piston — the  most  usual  design  being  to  make  them  equal — thus 
reducing  the  compression  ratio,  and  by  carefully  regulating  the 
weight  of  the  flywheels.  In  short,  the  long  stroke  and  high  com- 
pression of  the  early  Daimler  motors  have  been  found  generally 
impracticable  for  vehicle  work.  With  the  De  Dion  carriages 
having  the  motor  directly  geared  to  the  differential  the  com- 
pression of  the  motor  may  be  used  as  a  form  of  auxiliary  brake, 
especially  in  coasting  down  hills,  by  simply  interrupting  the 
electrical  ignition  circuit  and  leaving  the  clutch  connected — thus 
allowing  cycular  operations  to  be  directly  reversed,  the  road 


GASOLINE    MOTOR    DEVELOPMENT. 


309 


wheels  driving  the  motor  as  an  air-compressor.  Under  usual 
conditions  this  act  would  cause  the  motor  to  stop,  but  when  going 
down  hill,  with  the  clutch  in  gear,  the  motion  of  the  carriage 
will  drive  the  motor,  exactly  reversing  the  usual  order.  The  air, 
being  constantly  drawn  into  the  cylinder  space,  is  compressed  on 
the  in-stroke  of  the  piston,  thus  furnishing  sufficient  resistance 
to  materially  decrease  the  speed  of  the  carriage. 

In  connection  with  the  relation  of  stroke  length  and  neutral- 
izing of  vibration,  the  following  data  on  prominent  American 
gasoline  automobile  motors  will  be  of  interest : 


NAME. 

Number 
of 
Cylinders. 

Bore  in 
Inches. 

Stroke  in 
Inches. 

D.  H.  P. 

R.  P.  M. 

RATIO. 

Haynes-Appersofl.  . 
Peerless  

2 
2 
2 

5 
5V 
4^ 

5 

6K 

5l/2 

9 
i6 

I,OOO 
1,200 

I  —  I 
21  —  26 
9—II 

Packard  ... 

<  < 

I 

4 

6 

3^ 

6^ 

51A 

12 

20 

75° 

12-13 
V  —  41 

2  &4 

4 

5 

9  &  16 

900 

4  —  5 

Knox 

i 

c 

8 

8 

QOO 

S—  8 

2 

5 

7 

16 

5  —  7 

St.  Ivouis  

I 

5% 

6 

7 

500 

7—8 

Columbia 

4 

c 

c 

24 

QOO 

i  —  i 

« 

Stevens-Duryea  .  .  . 
Cadillac  
Franklin 

2 
2 
I 

4 

5 
4V 

& 

4K 

^y^ 

5 

T.I/ 

14 

6X 

IO 

'675 
800 

10  —  9 
19—18 
i  —  i 
i  —  i 

« 

4 

4 

c 

24 

4  —  5 

Autocar  

2 

4 

4 

II 

QOO 

i  —  i 

Stearns       

2 

53/ 

61/ 

24 

QOO 

2^  —  2"> 

Duryea   

1 

4^ 

4/4 

10^ 

QOO 

I  —  I 

Apperson  Bros  .  .  . 

Pope-Toledo  
Oldsmobile  

2 

4 

2  &4 

5% 

4V 
4*4 

ox 

5% 
6 

20 
40 
14  &  24 

4^ 

750 
500 
QOO 
60O 

23—26 

5-6 
17—21 

3  —  4 

Pope-Robinson.  .  .  . 
Ford 

4 

2 

4 
4 

6 

4 

8 

750 

2—3 

i  —  i 

Winton  .  . 

2 

sti 

6 

7—8 

It  will  be  seen  that  the  majority  of  these  engines  have  the 
piston  diameter  and  stroke  length  very  nearly  equal,  or  the  length 
of  the  stroke  very  little  greater  than  the  diameter.  The  Knox 
single-cylinder  engine  has  the  ratio  5  to  8,  and  the  double- 
cylinder,  5  to  7,  thus  producing  as  claimed,  the  longest  stroke 


310 


SELF-PROPELLED    VEHICLES. 


carriage  engine  made  in  this  country.  The  Knox  engines  are 
made,  however,  with  a  dome-shaped  compression  space,  thus 
reducing  the  compression  ratio  below  the  figure  that  would  other- 
wise seem  to  be  involved.  Only  two,  the  Stevens-Duryea  and  the 
Columbia  light  car,  have  a  piston-  diameter  greater  than  the  stroke 
length,  but  this  innovation  has  proven  advantageous  in  increasing 
power. 

The  Gobron=BriIIie   Motor. — While  the    familiar    types    of 
engine  would  seem  to  answer  all  requirements,  when  properly  de- 


FIG.  228.— The  Gobron-Brillie  Two-cylinder,   Four-piston  Balanced   Engine. 

signed  and  constructed,  several  inventors,  principally  Frenchmen, 
have  attempted  to  solve  the  vibration  problem  by  extraordinary 
mechanical  means.  The  most  noted  of  these  is  the  Gobron-Brillie 
double-cylinder  engine,  whose  four  pistons  work  upon  a  three- 
throw  crankshaft.  The  cylinders  are  open  at  both  ends,  two 
oppositely  moving  pistons  sliding  in  each,  with  the  valves,  ignition 
apparatus  and  compression  space  located  midway  in  the  length 
of  the  bore.  As  may  be  seen  from  the  figures  herewith  given,  the 


GASOLINE    MOTOR    DEVELOPMENT.  311 

lower  pistons  work  upon  one  crank,  and  the  two  upper  pistons, 
(through  a  crosshead  bar  at  the  top,  upon  two  other  cranks  set  at 
1 80°  from  the  first.  The  result  is  that  both  cylinders  have  the  out- 
strokes  and  in-strokes  of  their  pistons  simultaneous — the  power 
stroke  in  one  cylinder  taking  place  with  the  suction  stroke  in  the 
other.  According  to  the  statements  of  experts,  this  arrangement 
is  exceedingly  efficient  in  overcoming  motor  vibrations,  while  the 
highest  velocity  of  expansion  is  secured,  the  rate  being  nearly 
doubled,  as  compared  with  the  ordinary  type  of  motor.  Of 
course,  the  connecting  rods  between  the  upper  pistons  and  their 
cranks  must  be  twice  as  heavy  as  those  from  the  lower  pistons  to 
their  common  crank  pin.  Structually,  the  main  advantage  pre- 
sented is  that  all  joints  are  absent  in  the  cylinders ;  hence  no 
leakage  is  possible,  as  in  some  other  motors. 

The  De  Dion  Two=Cylinder  Motor. — De  Dion  &  Bouton  have 
attacked  the  vibrationless-cylinder  problem  very  differently. 
They  have  constructed  a  double  cylinder  motor,  the  two  pistons  of 
which  operate  two  cranks  on  the  same  line — virtually  working 
one  crank,  like  other  double  cylinder-motors.  Between  the  two 
power  cylinders,  however,  is  a  third,  in  which  slides  a  piston 
geared  to  a  crank  at  180°  from  the  other  two.  This  third  piston  is 
used  solely  for  balancing,  having  no  function  either  in  transmit- 
ting power  impulses  or  in  compressing  gas.  In.  order  to  obtain 
perfect  results,  the  balancing  piston  and  its  connecting  rod  must 
be  of  exactly  the  same  weight  as  the  two  power  pistons  with  their 
connecting  rods,  and  since  it  always  moves  in  the  opposite 
direction  from  them,  it  is  extremely  efficient  in  equalizing  the 
stresses  of  motor  operation.  The  end  of  perfect  balance  is  further 
advanced  by  the  use  of  two  flywheels,  one  at  either  end  of  the 
motor  shaft.  The  valves  are  operated  by  worm  gears  on  drums 
at  either  end  within  the  crank  case.  A  third  worm  gear  rotates 
a  pinion  governing  the  oil  circulation  in  a  manner  both  interesting 
and  effective.  As  shown  by  the  dotted  lines  in  the  drawing,  oil 
ducts  are  drilled  throughout  the  crank,  shaft,  piston  rods  and 
wrist  pins,  being  forced  by  the  pump  through  all  these  ducts  to 
the  several  bearings  and  to  the  cylinder  walls,  from  the  leads  LL, 
opening  at  the  top  of  the  crank  case.  Leakage  of  oil  is  prevented 
by  special  grard  bearings  at  OO,  the  surplus  of  oil  being  caught 
in  the  wall,  W. 


312 


SELF-PROPELLED   VEHICLES. 


Automatic  Governing  Devices.— Next  in  importance  to  se- 
curing perfect  balance,  when  the  motor  is  running  evenly,  is  the 
question  of  regulating  the  speed,  so  as  to  prevent  racing  of  the 
motor  and  loss  of  proper  control.  For  this  reason  most  gasoline 
vehicle  engines,  from  the  days  of  Daimler's  first  carriages,  have 
been  fitted  with  some  sort  of  automatic  governing  device.  As 
already  stated,  such  devices  have  operated  either  to  prevent  the 


AUTOMOBILE. 

FIG.   229.— The    De    Dion    &    Bouton    Two-cylinder,     Three-piston     Balanced 
Engine. 

opening  of  the  exhaust  valve,  to  retard  the  spark,  or  to  modify  the 
fuel  mixture.  In  accompanying  diagrams  are  shown  various 
types  of  device  for  governing  gasoline  engines.  The  first  repre- 
sents the  general  type  used  with  Daimler's  early  engines.  Here  a 
centrifugal  ball  governor  acts  to  shift  the  sliding  sleeve  on  the 
governing  shaft,  and  to  draw  away  the  pick  blade  used  to  push 


GASOLINE    MOTOR    DEVELOPMENT. 


313 


up  the  end  of  the  exhaust  valve  rod,  from  the  path  of  the  actu- 
ating cam.  .This  type  of  governing  is  more  frequently  used  on 
stationary  gas  engines,  and  is  very  effective ;  reducing  excessively 
high  speed  by  simply  preventing  the  burned  gases  from  escaping 
from  the  cylinder.  In  this  act  it  also  interrupts  further  supply  of 
fuel,  thus  interfering  with  the  operation  of  the  engine  until  the 
speed  is  reduced  again  to  the  proper  point.  In  later  Daimler 
engines  the  sliding  sleeve  operated  to  shift  the  position  of  a  lever 


.  230.— Diagram  of  the  Winton  Pneumatic  Speed  Control  System.  A  is 
the  valve  chamber  from  which  the  air  is  exhausted  through  the  vent, 
G,  by  pressure  on  the  foot  button  at  the  top  of  the  valve  rod;  B,  a 
tube  connecting  chamber,  A,  with  air  reservoir,  C;  D,  tube  leading 
from  the  air  pump  operated  from  the  main  shaft  of  the  engine,  and 
feeding  compressed  air  into  the  reservoir,  C;  E,  the  piston  attached  to 
the  spindle  of  the  inlet  valve,  F,  and  controlling  the  opening  of  F,  ac- 
cording to  the  degree  of  compression  maintained  within  reservoir,  C. 
By  this  mechanism  the  opening  of  the  inlet  valve,  and  consequently 
the  fuel  supply,  is  regulated  within  definite  limits,  and  the  speed  varied 
as  desired. 


connected  through  a  link  with  the  end  of  the  valve  rod,  the  end  of 
the  valve  rod  being  pushed  away  from  its  normal  support,  and  out 
of  the  path  of  the  actuating  cam,  as  is  shown  in  the  accompanying 
illustration.  A  much  more  practical  device  is  the  Peugeot  vari- 
able exhaust  valve  lift,  in  which  the  end  of  the  exhaust  valve  rod 
is  attached  to  a  lever,  whose  fulcrum  is  shifted  by  the  action  of  the 
governor  from  a  point  at  which  the  movement  of  the  cam  pro- 
duces the  greatest  lift  of  the  valve,  to  a  point  at  which  the  valve. 


314  SELF-PROPELLED    VEHICLES. 

is  left  completely  stationary.    The  operation  may  be  understood 
by  the  illustration. 

Winton's  Pneumatic  Control. — Very  many  gasoline  carriages 
of  American  build  have  no  automatic  regulation  of  the  engine, 
depending  for  speed  and  power  control  solely  upon  the  acUof  the 
chauffeur.  Of  this  kind  is  the  Winton  pneumatic  regulator  for 
controlling  the  inlet  valve,  as  shown  in  an  accompanying  figure. 
The  details  are  as  follows :  A  small  air  pump,  drive,ti  by  a  con- 


FIG.  231.— The  Sliding  Cam  Ignition  Governor  of  the  "Packard"  Carriages. 
A  is  a  sleeve  sliding  on  a  feather,  B,  on  the  rotating  shaft,  being  con- 
nected by  link,  D,  to  the  governor  weight,  E,  so  that  the  throw  of  the 
cam,  F,  may  be  varied  from  maximum  to  zero,  as  the  speed  of  the 
motor  increases.  Cam,  F,  bears  upon  the  roller  carried  on  the  end  of 
the  vibrating  leaf  spring,  G,  modifying  the  electrical  contact  between 
the  terminals,  J  and  K,  according  to  the  throw  of  the  cam  and  the 
adjustment  of  the  screw,  H. 

necting  rod  from  an  eccentric  on  the  main  shaft,  which  is  fixed 
at  1 80°  from  the  crank,  constantly  supplies  air  to  a  special 
reservoir  where  it  bears  upon  a  piston  fixed  at  the  end  of  the  rod  of 
the  cylinder  inlet  valve,  so  that,  according  to  its  pressure,  it  can. 
control  the  amount  of  fuel  admitted  to  the  combustion  space. 
The  operation  is  very  simple  and  reliable,  since  the  air  behind  the 
piston  just  mentioned  can  escape  only  when  the  push  button, 
coming  through  the  floor  to  the  driver's  foot,  is  depressed.  It 
consequently  follows  that  when  the  speed  of  the  engine  has  ex- 


GASOLINE    MOTOR    DEVELOPMENT. 


315 


ceeded  a  certain  predetermined  limit  the  air  exhaust  cannot  take 
place  with  sufficient  rapidity  to  enable  the  usual  operation  of  the 
feed  valve  to  continue ;  hence  it  acts  as  a  cushion  or  spring", 
resisting  the  opening  of  the  feed  valve  until  the  speed  has  again 
sunk  to  the  desired  point.  By  pressing  on  this  button  the  speed 
of  the  engine  may  be  varied  through  a  range  between  100  and 
800  revolutions  per  minute. 


AUTOMOBILE. 


FIG.  232.— Diagram  of  Volume  Throttling  Device  on  the  Mors  .Engine.  A 
and  A  are  throttle  valves  on  the  inlet  pipes;  B  and  B,  valve  levers;  C, 
valve  shaft,  under  control  of  the  governor,  D;  B  and  F,  springs,  used 
either  singly  or  together,  according  to  control,  so  as  to  vary  the  open- 
ing of  the  inlet.  System  like  the  Duryea. 

The  Packard  Ignition  Governor. — Another  American  car- 
riage, the  Packard,  is  equipped  with  a  foot-operated  inlet-valve 
controller,  by  which  the  speed  of  the  motor  may  be  regulated  up 
to  850  revolutions  per  minute.  In  addition  to  this,  there  is  a  very 
ingenious  governing  device  operating  from  the  camshaft  to  the 
motor,  which  at  high  speed  modifies  the  spark  to  any  required 
point,  or  prevents"  it  altogether,  This  result  is  accomplished  by 


316 


SELF-PROPELLED    VEHICLES. 


a  sliding  sleeve,  actuated  by  the  centrifugal  governor,  which 
moves  a  variable  cam  across  the  periphery  of  a  roller  attached 
to  a  contact  spring  used  to  make  the  ignition  circuit.  When  the 
speed  of  the  motor  exceeds  a  predetermined  limit,  the  cam  over- 
runs the  roller  and  ignition  is  prevented.  The  variable  cam  also 
has  a  toe  lying  screwwise  around  the  sleeve,  so  that  it  actuates 
the  roller  sooner  at  high  speed  than  low  speed,  thus  automatically 
timing  the  ignition  as  nearly  as  possible  to  the  proper  moment 
for  maximum  efficiency. 


A 


FIG.  233.— Automatic  Governor  and  Hand  Throttling  Connections  of  the 
Toledo  Motor.  The  parts  are:  A,  the  suction  pipe  of  the  carburetter; 
B,  the  carburetter;  B',  the  needle  valve  on  the  float  chamber;  C,  the 
float  chamber;  D,  throttle  controller  on  rod,  E;  F,  the  governor  lever; 
G,  the  sliding  governor  sleeve;  H,  governor  weight;  J,  fibre  gear  on  cam 
shaft;  K,  sparking  commutator;  L,  cam  shaft. 

Throttling  Governors. — The  majority  of  modern  motors  have 
apparatus  by  which  the  time  of  the  spark  may  be  regulated  by 
the  driver,  and  with  very  many  of  them  the  same  result  is 
achieved  by  automatic  governing.  In  many  senses,  however, 
throttling  seems  to  be  the  most  approved  method  of  governing. 
With  the  Centaure  motor  of  Panhard-Levassor  the  centrifugal 
governor  acts  to  move  a  sleeve  along  its  shaft,  and  thus,  at  high 
speeds,  to  reduce  the  quantity  of  gas  mixture  coming  from  the 
carburetter,  through  a  piston  rod,  link  and  lever,  as  shown  in  an 
accompanying  diagram,  The  same  result  may  be  achieved  at 


GASOLINE    MOTOR    DEVELOPMENT. 


31Y 


the  will  of  the  driver  by  means  of  a  foot  pedal  or  hand  lever — 
often  both  are  provided — independent  of  the  mechanical  condi- 
tions in  which  the  governor  operates.  A  very  similar  arrange- 
ment is  used  on  the  Pope-.Toledo ;  the  hand-throttling  gear  oper- 
ating on  the  same  link  as  the  automatic  centrifugal  governor. 
The  arrangement  of  the  throttling  and  spark-control  handles  is 
shown  in  a  previous  diagram  of  the  steering  wheel  of  this  car- 
riage. 


HORSELESS  AGE. 

FIG.  234.— Centrifugal  Governor  of  the  Locomobile  Car- 
riage. A,  pinion  on  the  main  shaft ;  B,  two-to-one  gear 
on  second  shaft,  carrying  governor  mechanism;  C, 
small  gear  for  driving  a  dynamo  and  circulating  pump; 
D,  D,  levers  pivoted  to  lugs  on  rim  of  B  ;  E,  E,  governor 
balls;  F,  F,  governor  springs;  G,  G,  links  connecting 
lever  arms  to  double  armed  bracket,  H,  turning  it  when  the  balls  fly  out  to  posi- 
tions shown  by  dotted  lines ;  L,  commutator  wheel  of  ignition  circuit-maker ; 
M,  M,  lateral  studs  on  bracket,  H ;  N,  grooved  collar  rotated  by  studs ;  O,  sleeve 
on  N,  having  a  spiral  slot  which  works  on  pin,  P. 

The  Riker  Governor. — The  governor  used  on  the  Locomobile 
gasoline  carriage,  for  automatically  effecting  the  throttling  of 
the  carburetter  and  the  retarding  of  the  spark,  is  a  good  example 
of  the  designer's  skill.  As  shown  in  the  accompanying  diagrams, 
the  arms  carrying  the  governor  weights  actuate  links  at  right 
angles  to  their  normal  position,  and  cause  a  sleeve  on  the 
governor  shaft  to  turn  on  the  shaft  through  part  of  a  revolu- 
tion, according  to  the  speed  of  the  motor.  The  part  rotation  of 
this  sleeve  serves  to  retard  the  spark  by  shifting  the  contact  of 


318  SELF-PROPELLED   VEHICLES. 

the  sparking  commutator.  At  the  same  time,  two  pins,  attached 
to  the  sleeve  arms  and  projecting  through  the  gear  into  the 
opposite  direction,  give  a  similar  turn  to  the  governor  shipper 
loosely  let  on  to  the  governor  shaft.  This  shipper  has  a  hub  with 
a. spiral  groove,  through  which  projects  a  pin  fixed  into  the 
shaft,  as  shown.  By  the  part  revolution  given  the  shipper  by 
the  pins  the  hub  moves  backward  along  the  shaft  as  far  as  the 
pin  in  the  groove  will  allow  it,  thus  actuating  a  link  for  throttling 
\the  carburetter.  As  the  engine  slows  down,  the  sleeve  holding  the 
commutator  cam  returns  to  its  position,  and  the  pins  acting  on 
the  shipper  move  the  slotted  hub  into  normal  position,  restoring 
fche  full  feed  of  fuel  mixture.  In  starting  the  motor,  the  driver 


FIG.  235.— Diagram  of  the  Governor  and  Control  Connections  of  the  Loco- 
mobile Carriage,  showing  manner  of  automatically  and  manually 
throttling  the  carburetter. 

reverses  the  lead,  retarding  the  spark  until  the  full  speed  is  at- 
tained, then  leaving  control  to  the  governor. 

Gasoline  Motor  Construction. — In  the  construction  of  gaso- 
line engine  cylinders  experience  has  pretty  clearly  established 
one  point — that  the  cylinder,  with  explosion  and  valve  chambers, 
should  be  cast  in  one  piece,  and  that  no  joints  to  be  closed  by 
bolts  and  gaskets  should  exist  above  or  behind  the  power  face 
of  the  piston.  While  all  manufacturers  do  not  adhere  strictly 
to  this  rule,  it  nevertheless  remains  true  that  many  difficulties 
have  been  experienced  with  leaking  joints,  and  that  the  plan  of 
avoiding  them  altogether  is  followed  by  some  of  the  best  authori- 
ties in  the  automobile  world. 


GASOLINE    MOTOR    DEVELOPMENT.  319 

Exhaust  Valves. — In  regard  to  the  operation  of  the  exhaust 
valves,  the  standard  practice  is  to  open  with  a  pushrod  operated 
by  a  rotating  cam,  rather  than  by  the  use  of  eccentrics  and 
straps  or  by  grooved  discs  of  the  Daimler  type.  Regarding 
eccentrics  it  may  be  stated  that  they  are  used  on  a  few  motors 
that  have  the  inlet  valves  positively  geared,  but  are  not  popular 
for  ordinary  purposes.  The  Daimler  grooved  disc  arrangement 
was  revived  some  years  since  in  a  bicycle  motor,  as  shown  in  a 
Fig.  287,  but  are  practically  abandoned  on  carriage  motors,  in 
favor  of  the  more  reliable  shaft  cam. 

Positively  Operated  Inlets. — Several  recent  motors  have  the 
inlet  valves  positively  operated  either  by  shaft  cams  or  eccentrics. 
The  object  sought  is  to  render  the  operation  of  the  valve  perfectly 
regular,  preventing  breakage  from  rapid  movements ;  also  to 
allow  of  a  higher  initial  pressure,  since  none  of  the  force  of 
suction  •  is  expended  in  maintaining  the  compression  of  the  valve 
spring,  and  a  greater  quantity  of  fuel  mixture  can  enter  the 
cylinder.  Other  authorities  object  to  this  arrangement  on  the 
grounds  of  economy  and  efficiency.  Thus  one  prominent  manu- 
facturer says: 

"Experience  has  taught  that  the  positive  cam-actuating  inlet 
valve  is  not  nearly  as  efficient  as  the  older  forms.  We  are 
able  to  state  this  positively,  having  been  pioneers  of  positive 
action  construction,  which  has  been  discarded  by  us  for  the  past 
two  seasons.  The  reason  for  this  change  is  not  hard  to  seek, 
as  in  the  positive  valve  type  it  is  necessary,  unless  the  walking- 
beam  system  is  resorted  to,  to  allow  a  large  compression  space 
in  the  head,  which  absolutely  reduces  compression  in  itself  and 
causes  a  loss  of  power.  The  walking-beam  system  causes  com- 
plication and  trappiness.  The  automatic  system  is  free  of  this 
objection,  and  with  the  advent  of  nickel-steel  in  valve  construc- 
tion, the  question  of  breakage  of  these  rapidly  moving  parts  has 
been  satisfactorily  solved." 

The  facts  remain,  however,  that  several  manufacturers,  claim- 
ing as  high  a  speed  capacity  as  between  800  and  900  revolutions 
per  minute,  which  is  the  average  for  the  engine  mentioned  in  the 
above  quotation,  still  use  positively-operated  inlet  valves,  and 
claim  good  results.  Several  of  the  best  makes  of  French  car- 
riage motor  now  have  the  positively-operated  inlet  valves,  .notable 
among  these  being  the  Mors,  Darracq  and  Decauville. 


320 


SHIP-PROPELLED 


Gasoline  Motor  Development. — While  the  earliest  carriages 
built  on  the  Daimler  models  used  motors  that  embodied  the 
original  theories  of  the  inventor — high  piston  speeds  and  a  stroke 
sweep  long  in  proportion  to  the  diameter  of  the  piston — designs 
were  gradually  modified  so  as  to  approximate  models  accepted 
at  the  present  day.  In  the  V-shaped  engines  used  on  the  earliest 


FIG.  236.— The  Panhard-Levassor,  40  Horse-power  "Centaure"  Motor.  A 
and  A,  tubes  leading  to  and  from  the  carburetter,  the  one  on  the  left 
for  conveying  hot  air  from  near  the  combustion  space,  that  on  the 
right  for  feeding  the  mixture  into  the  cylinders;  B,  B,  B,  B,  sparking 
plugs;  C,  mixing  chamber  of  the  carburetter;  E,  E,  nuts  securing  yokes 
for  holding  inlet  valve  chambers  in  place;  F,  float  chamber  of  carbu- 
retter; G,  G,  G,  G,  ports  for  attaching  lubricating  tubes;  J.  J,  cylinder 
head  plates;  M,  M,  hangers  for  attaching  motor  to  carriage  frame;  R, 
gear  on  two-to-one  shaft  carrying  governor  mechanism;  S,  gear  on 
main  shaft;  V,  flywheel;  a,  port  for  admitting  gasoline  to  the  carbu- 
retter. 


Daimler  carriages  the  ratio  between  piston  diameter  and  stroke 
length  was  as  3  is  to  5.  For  the  purpose  of  obtaining  superior 
balance  and  better  efficiency,  this  was  gradually  reduced,  until 
in  the  Phenix-Daimler,  double-cylinder,  6  horse-power  motor  of 
1899,  the  figures  were  3  and  4 — the  piston  diameter  being  90  mm. 


GASOLINE    MOTOR    DEVELOPMENT. 


321 


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SELF-PROPELLED    r 


(3.54.  inch)  and  the  stroke  length  120  mm.  (4.72  inch).  This 
motor  developed  6  horse-power  at  700  revolutions.  The  clear- 
ance space  was  concaved,  and  the  compression  pressure  was  60 
pounds.  As  shown  in  the  accompanying  illustration,  the  Daimler 
shaft-cam  governor  was  used  for  automatic  regulation  of  speed. 
The  two  cranks  were  set  at  180°.  The  castings  were  in  four 


FIG.  238.— Section  of  the  Krebs  Mixer  used  with  the  later  Panhard-Levassor 
Engines.  The  float  chamber  and  other  parts  are  identical  with  the 
Centaure  carburetter.  Gasoline  comes  from  the  float  chamber  through 
channel,  P,  and  spraying  nozzle,  L,  air  being  admitted  at  K.  Q  is  the 
mixing  chamber  from  which  the  air  and  gasoline  gas  passes  into  the 
feed  tube,  M,  through  the  port,  H,  whose  opening  is  controlled  by  the 
position  of  the  serrated  perforations  in  piston,  O,  moving  through  bore, 
R,  as  controlled  by  the  governor  through  piston  rod,  S.  When  more 
air  than  the  fixed  quantity  admitted  at  K  is  required  by  the  condi- 
tions of  motor  operation,  the  suction  of  the  motor  piston  depresses  the 
small  piston,  A,  held  in  cylinder,  F,  by  the  spring,  E,  and  sliding  in 
the  elastic  diaphragm,  C.  Air  is  admitted  above  it  through  a  small 
port  at  B.  The  depression  of  piston,  A,  and  causes  the  slide,  H,  to 
move  downward  in  tube,  G,  thus  opening  to  a  greater  or  less  degree 
the  ports,  J  and  J,  admitting  the  required  amount  of  air  for  any  given 
condition. 

parts;  the  cylinder  heads  and  valve  chambers  being  separable 
from  the  cylinders,  and  the  crank  chamber,  consisting  of  an  upper 
and  a  lower  member,  bolted  together  on  flanges,  as  shown.  The 
Phenix,  or  modified  Maybach,  carburetter,  already  described, 
was  used  with  this  engine,  and  the  Panhard-Levassor  clutch  and 
speed  gear  transmitted  its  power  to  the  road  wheels. 


GASOLINE    MOTOR    DEVELOPMENT. 


323 


Multiple  Cylinders:    The  Panhard. — .The  demand  for  high- 
speed high-powered  cars  led  very  soon  to  the  production  of  four- 


FIG.  239.— Section  of  the  De  Dion  &  Bouton  Water-jacketed  Carriage  Motor, 
Parts  are  as  follows:  A,  crank  case  formed  by  two  cylindrical  pieces 
bolted  together;  B,  the  inlet  valve  for  the  fuel  mixture  from  the  carbu- 
retter; C,  the  exhaust  valve,  held  closed  by  a  helical  spring,  F,  and 
opened  by  the  cam,  H;  D,  the  opening  for  the  compression  tap;  E,  the 
threaded  hole  for  the  sparking  plug;  F,  the  spring  on  the  exhaust  valve 
rod;  G,  the  cylinder;  I  the  port  of  exit  for  the  jacket  water  from 
jacket,  J,  the  inlet  being  at  a  point  near  the  base  of  the  jacket;  K 
and  K  are  the  flywheels,  or  crank  discs,  which  are  joined  together  as 
shown,  by  the  crank  pin,  N;  M  is  the  connecting  rod;  N  is  the  crank 
pin;  O  and  O  are  the  crank  shafts,  that  on  the  right  carrying  the 
pinion,  P,  that  on  the  left  being  threaded  for  connection  to  the  driving 
gear;  P  is  a  pinion  on  the  crank  shaft  meshing  with  gear,  Q. 

cylinder  motors,  of  which  the  Panhard-Levassor  Centaure  is  the 
type.  The  4O-horse-power  motor  is  shown  in  an  accompanying 
illustration.  Here,  as  mav  be  seen,  the  four  cylinders  are  cast 


SELF-PROPELLED    VEHICLES. 

in  two  separate  pairs  integral  with  their  valve  chambers ;  each 
pair  being  capped  by  head  plates  bolted  to  the  casting.  The 
automatic  carburetter  control  and  manual  throttling  connections 
are  plainly  shown,  also  the  common  fuel  feed  and  hot  air  tubes 
AA.  This  is  essentially  the  model  of  motor  still  used  on  heavy 
Fanhard  carriages ;  its  simplicity  and  high  efficiency  having  con- 
tributed to  its  well-earned  popularity.  As  may  be  seen  from  the 
cut,  the  ratio  of  diameter  and  stroke  length  is  about  the  same 
as  that  of  the  Phenix.  Attachment  to  the  carriage  frame  is  by 
the  hangers,  MM. 

The  De  Dion  One  Cylinder  Motor. — The  De  Dion  motors 
were  among  the  earliest  improvements  on  the  original  Daimler 
models.  The  aim  sought  in  their  design  was  to  attain,  complete 
balance  of  motion  with  a  single  cylinder  and  this  was  accom- 
plished, as  already  suggested,  by  the  use  of  carefully-calculated 
heavy  flywheels  and  equalization  of  the  stroke  length  and  cylinder 
diameter.  In  the  single-cylinder  light  carriage  motor,  a  diameter 
and  stroke  of  80  millimeters  (3.15  inches)  enables  the  develop- 
ment of  between  5  and  6  horse-power  at  1,800  revolutions.  As 
shown  in  the  section,  the  cylinder,  head,  water  jacket  and  valve 
chambers  are  cast  integral ;  no  joint  existing  above  the  power  face 
of  the  piston,  save  the  opening  for  the  compression  tap  at  D. 
This  type  of  motor,  long  noted  for  high  efficiency,  is  intended  to 
be  direct-connected  through  the  speed  gear  with  the  rear  axle,  as 
suggested  in  other  places.  It  is  peculiar  among  carriage  motors 
in  having  the  two  flywheel  discs — a  further  contribution  to 
balancing  movement — enclosed  in  the  crank  case,  with  the  crank 
pin  inserted  upon  a  radius  of  both.  Double  cylinder  De  Dion 
motors,  both  with  and  without  the  balancing  piston,  are  now  made 
for  heavy  carriage  and  wagon  use ;  the  former  type  being  the 
favorite  for  heavy  trucks. 

The  Packard  Engine. — The  Packard  four-cylinder  engine 
is  typical  of  the  class  having  positively-operated  inlet  valves. 
Unlike  the  majority  of  such  engines,  however,  both  inlets  and 
exhausts  are  operated  from  one  cam  shaft  on  the  same  side  of  the 
cylinders.  With  most  typical  engines  of  this  class  two  cam- 
shafts, each  operated  by  two-to-one  gearing  from  the  main  shaft, 
are  set  on  opposite  sides  of  the  engine,  so  that  the  inlet  valve 


GASOLINE    MOTOR    DEVELOPMENT. 


325 


chambers  are  opposite  to  the  outlets.  Such  an  arrangement  is 
shown  in  the  plan  view  of  the  Decativille  carriage.  The  object 
of  this  latter  arrangement,  which  is  reproduced  by  the  American 
Peerless  engine,  and  others,  is,  of  course,  to  allow  sufficient  room 
for  the  supply  and  exhaust  pipes  to  the  cylinders.  With  the  Pack- 
ard engine  the  supply  pipe  is  carried  from  the  carburetter,  set  on 
the  right  side  of  the  engine,  over  the  top  between  the  two  middle 
cylinders,  as  shown  in  the  sectional  elevation  and  plan  views  of 
the  carriage,  In  the  section  of  the  engine  the  inlet  valve  cham- 


FIG.  240.— Part  Sectional  Elevation  of  the  Packard  Four-cylinder  Motor, 
showing  method  of  driving  the  inlet  and  exhaust  valves  from  a  single 
cam  shaft. 


bers  are  seen  at  the  outside  ends  of  each  pair  of  cylinders,  the 
exhausts  being  placed  between  them.  As  shown  in  the  elevation 
of  the  carriage,  the  exhaust  is  carried  off  at  the  left  side  to  the 
muffler.  On  the  right  side  is  also  the  entrance  for  the  jacket 
water,  which  is  let  off  at  the  top  between  the  cylinders  of  each 
pair.  The  jackets  completely  cover  the  long  sweep  of  the  pistons. 
The  oil  duct  to  the  crank  case  carries  oil  down  between  the  pairs 
of  cylinders,  The  commutator  is  operated  by  bevel  gearing  from 


SELF-PROPELLED    VEHICLES. 


the  cam  shaft,  being  shown  at  the  top  of  the  vertical  spindle 
to  the  right  of  the  diagram. 

The  oil  is  distributed  by  a  force  pump  operated  by  an  80  to  i 
reduction.  It  has  four  ball  valves  controlled  by  tension  springs, 
to  balance  the  siphoning  of  the  oil  column. 

American  Motor  Development. — Motor  development  in 
America  may  be  said  to  have  been  almost  independent  of  things 


FIG.  241.— Single  Cylinder  Motor  of  the  St.  Louis  Gasoline  Motor  Carriage, 
showing  control  levers  and  the  variable  speed  gear  contained  within  the 
case  below  the  crank. 

done  abroad.  As  in  every  other  mechanical  branch,  designers 
and  inventors  sought  from  the  first  to  produce  something  dis- 
tinctive, and  were  inclined  to  reject  the  achievements  of  French 
engineers,  whose  products  often  seem  needlessly  complicated  to 
the  American  mind.  Thus  it  was  that  the  standard  motor  models 
of  Daimler  and  Panhard-Levassor  were  rejected  in  favor  of  some- 


GASOLINE    MOTOR    DEVELOPMENT. 


327 


thing  yet  to  come  that  should  be  thoroughly  original.  The  typical 
European  shift-gear  transmissions  were  also  rejected  for  the 
planetary  and  constantly  meshed  types,  which  may  be  said  to  be 
America's  real  contributions  to  automobile  development. 

It  may  not  be  too  much  to.  say  that  all  distinctly  American 
motor  carriages  have  begun  their  history  with  the  single-cylinder 
motor.  This  was  the  case  with  the  Duryeas,  Winton  and  several 


FIG.  242.— Four-cylinder  Motor  of  the  Locomobile  Carriage.  D,  dynamo;  HJ, 
exhaust  pipe;  F,  flywheel;  G,  governor;  H,  air  heater  for  carburetter; 
L,,  lug  on  cylinder  wall,  as  fulcrum  for  tool  in  removing  exhaust  valves; 
P,  centrifugal  pump;  O,  oil  tank;  S,  S,  S,  S,  spark  plugs. 

other  pioneers.  To-day  we  have  the  three-cylinder  Duryea  car- 
riages and  the  double-opposed  cylinder,  Stevens-Duryea.  Win- 
ton  has  followed  the  general  development  and  is  now  building 
a  double-cylinder  motor  with  several  original  features.  Other 
popular  carriages,  such  as  the  Packard,  the  St.  Louis,  the  Knox, 
all  staunch  advocates  of  the  single  cylinder,  have  latterly  adopted 
double  cylinders.  Only  the  light  Oldsmobile,  the  Cadillac  and  the 


328  SELF-PROPELLED    VEHICLES. 

Crest  among  light  carriages  adhere  strictly  to  the  original  plan. 
However,  most  of  the  cars  of  recent  origin  are  driven  by  2  or 
4-cylinder  motors,  and,  as  we  shall  presently  learn,  the  general 
tendency  among  such  is  toward  following  the  designs  set  down  by 
French  prototypes. 

The  Riker  Motor. — Among  the  most  interesting  of  recent 
American  carriage  motors  is  that  used  on  the  Riker-Locomobile 
carriages.  There  are  two  models;  the  2-cylinder,  9  horse-power 
and  the  4-cylinder,  16  horse-power,  both  capable  of  a  25%  out- 
put above  rating  at  increased  speed.  Both  have  a  piston  diameter 
of  4  inches  and  a  stroke  of  5  inches,  developing  their  rated  power 
at  900  revolutions.  Each  pair  of  cylinders  is  cast  in  one  piece 


FIG.  243.— View  of  Locomobile  Motor  Inlet  Valves,   showing  ease  with  which 
they  may  be  removed. 

with  the  heads,  water  jackets  and  valve  chambers,  according  to 
the  design  most  widely  approved  by  American  engineers.  A 
particularly  interesting  structural  feature  is  found  in  the  intake 
valve  chambers,  which  are  closed,  so  as  to  be  readily  accessible 
by  cone-shaped  bonnets  held  in  place  by  yoke  covers,  readily  de- 
tachable by  means  of  a  single  clamping  bolt,  as  shown  in  ac- 
companying figures. 

Each  2-cylinder  casting  is  bolted  to  the  upper  member  of  the 
crank  case, '  which  is  of  bronze,  the  lower  member  being  of 
aluminum.  .The  former  carries  arms  for  attaching  the  motor 
to  the  frame  of  the  wagon.  The  main  shaft  of  the  four-cylinder 
engine  is  in  one  piece,  consisting  virtually  of  two  double-throw 


GASOLINE    MOTOR    DEVELOPMENT. 


329 


parts,  the  cranks  in  each  being  set  at  180°.  The  inlet  valves  are 
operated  by  suction,  and  the  exhaust  from  cams  rotated  by  a  two- 
to-one  reduction  from  the  main  shaft.  A  third  parallel  shaft, 
carrying  the  sparking  dynamo  and  circulating  pump,  is  rotated 
through  a  large  gear  on  the  cam  shaft.  In  case  of  accident  to  the 
pump  the  circulation  system  is  so  arranged  that  the  deficiency 


Sparkplug 


Oil  tank 


]  I  [  JZchaitsl  passage 


FIG.    244. — Section    of    One-cylinder    of    Locomobile    Four-cylinder    Gasoline 
Engine. 

may  be  supplied  by  gravity  at  any  time.  The  ignition  circuit  is 
supplied  at  starting  by  a  battery  of  two  4O-ampere-hour  storage 
cells,  which  are  automatically  cut  out  when  the  dynamo  has  taken 
up  speed.  A  separate  coil  for  each  cylinder,  makes  the  coti- 
.nection  of  every  plug  separate.  In,  the  special  non-sooting  plug 


330  SELF-PROPELLED   VEHICLES. 

designed  for  this  motor,  an  annular  space  between  the  porcelain 
core  and  metal  housing,  provides  a  vortex  with  each  alternate 
compression  and  expansion,  carrying  off  any  carbon  deposits  re- 
sulting from  the  ignition  of  the  charge.  .The  outside  spark-gap  in 
the  form  of  a  chain  connection-  between  cable  terminal  and  plug 
ensures  sparking,  even  when  deposits  have  collected.  This  is  a 
feature  now  popular  in  a  large  variety  of  forms,  of  which  Mr. 
Riker  claims  to  have  been  the  first  discoverer  in  this  country. 

The  lubricating  system  is  of  interest,  as  securing  an.  even  flow 
of  oil  and  preventing  excess.  The  supply  tank  is  set  at  the  head 
of  the  stand  pipe  beside  the  cylinder  head,  the  viscosity  of  the  oil 
being  maintained  by  the  heat  of  the  wall.  The  stanclpipe  leads 
oil  to  the  crank  case,  and  the  interior  of  the  cylinder  is  evenly 
lubricated  by  splashing.  Excess  is  prevented  by  a  groove  on  the 
inner  circumference  near  the  lower  end  of  the  piston  sweep, 
where  the  overflow  may  be  collected  into  a  vertical  return  pipe 
parallel  with  the  main  feeder,  as  shown.  Overflow  pipes,  extend- 
ing into  the  crank  case  to  the  required  level,  enable  the  excess  to 
be  drawn  off  through  cocks.  The  governor,  already  described, 
is  carried  on  the  two-to-one  secondary  shaft. 

The  Pope=Toledo  Motor. — The  engine  of  the  Pope-Toledo 
car  is  a  good  modern  example  of  high  compression  motor.  It  is 
made  in  2  and  4-cylinder  models,  developing,  respectively,  14  and 
24  horse-power  at  900  revolutions.  The  end  of  perfect  balance  in 
each  cylinder  is  attained  by  the  use  of  a  very  long  piston,  carrying 
an  additional  expansion  ring  near  its  forward  end,  as  shown  in 
the  sectional  cut.  Each  cylinder  is  cast  separate  without  a  water 
jacket,  that  addition  being  supplied  by  a  corrugated  copper  tube 
let  over  the  outside  circumference,  being  sweated  and  soldered 
in  grooved  flanges.  The  valve  chambers  are  cast  separate,  form- 
ing a  head-piece  to  the  cylinder,  which  is  bolted  to  the  flanges. 
The  lower  end  of  the  cylinder  projects  into  the  crank  case,  to 
which  it  is  secured  by  flanges  and  bolts.  The  inlet  valves  are  oper- 
ated by  suction  and  the  exhaust  from  a  two-to-one  camshaft,  after 
the  usual  plan.  Special  care  is  takejn  with  every  detail  of  this 
motor,  mathematical  refinements  being  continued  even  to  the 
finishing  of  the  piston  rings  by  hand,  all  of  which  adds  greatly 
to  its  efficiency  and  the  ease  of  operation.  According  to  test, 
this  motor  appears  to  be  almost  as  noiseless  as  a  steam  machine. 


GASOLINE    MOTOR    DEVELOPMENT. 


331 


Perfect  balance  and  accurate  adjustment  are  further  advanced 
by  the  care  expended  in  making  the  bearings.  These  are  con- 
structed from  a  special  fomula  of  bronze  and  are  cast  in  halves, 


.  CYUmCHHUb 

2  CYLINDER 

3  FISTM 

4  CUMK CMC  UPPER HALf 

I  •••      •      LOWER HALF 
6  COWKCTIMIIOO 

?'  CRANK  MN 

r       PW 

9  BRASSES 

10  SNATTBEARHK 

II  PISTON  PIN 
12  RINCS 

19  WATER  JACKET  CASIN6 
14  INLET  PIPE 

IB  OUTLET  PIPE 

16  EXHAUST  PIPE 

17  INLET  VALVE 

18  SEATINC 

ia  sptiw 

20  RETAINER 

21  KET 
2t                    CAP 

?a  me 

24  SET  SCREW 

26    <  LOCK  mi 

Z6  YOKE  STUD 

Z  7  EXHAUST  VALVE 

28  •  STEM 


RETAINER 


14  •  CAHROLLEU 

?S  CAM 

35  SHAFT 

37  OUST CAP 

3SSnU»INCPLUC 

M 


41  CYLMOER HEAD  STUDS 
4»ELCrcOC< 

•U OIL  SCOOP 


A  INLET  CHAMBER 
B  COMPRESSION  SPACE 
C  EXHAUST MSSACC 
D  NKTCR  SPACE 


FIG.   245.— Section  through  one  Cylinder  of  the  Pope-Toledo   Motor,   showing 
parts  and  construction. 


accurately  surfaced  on  a  milling  machine,  soldered  together,  and 
the  whole  turned  in  a  lathe  so  that  the  outer  and  inner  surfaces 


332 


SELF-PROPELLED    VEHICLES. 


are  perfectly  true.     At  the  conclusion  of  this  rather  complicated 
process  they  are  carefully  hand-surfaced. 

The  Opposed-Cylinder  Motor. — The  double-opposed  cylinder 
engine  may  be  said  to  be  virtually  an  American  development,  al- 
though it  was  first  designed  and  patented  by  Daimler  in  1886,  and 
was  formerly  used  by  Mors,  -Henroid,  Gautier-Wehrle  and 
Turgan  &  Foy.  It  is  very  nearly  the  typical  construction,  in 
America  for  double-cylinder  motors  not  built  on  the  lines  laid 
down  by  Panhard-Levassor  and  other  French  designers.  Builders 


FIG.  246.— Sectional  Diagram  of  the  Haynes-Apperson,  Double  Opposed 
Cylinder  Motor,  showing  valve  arrangements  and  details  of  primary 
ignition  device. 

who  have  adopted  it  declare  that  it  is  the  type  best  adopted  to 
maintaining  good  balance  and  overcoming  vibration  when  two 
cylinders  are  used,  as  dispensing  with  the  single-throw  common 
crank,  and  giving,  as  nearly  as  possible,  an  even  weight  on  both 
sides  of  the  shaft.  Probably  the  earliest  American,  motor  of  this 
description  is  the  well-known  Haynes-Apperson,  which  has  been 
a  practical  reality  since  the  introduction  of  their  carriages  in 
1893-94.  So  complete  is  the  adjustment  of  the  moving  parts  of 
this  motor'  that  noise  and  vibration  are  reduced  to  a  minimum. 


GASOLINE    MOTOR    DEVELOPMENT. 


333 


The  manufacturers  assert  that  one  of  their  carriage  motors  has 
been  connected  to  operate  an  electric  light  dynamo,  and  run 
without  any  perceptible  variation  in  voltage,  even  when  the  con- 
nection is  direct  to  the  main  shaft. 

No  attempt  is  made  to  control  the  speed  of  the  engine  by  an 
automatic  governor,  the  method  employed  being  to  throttle  the 
charge,  thus  insuring  only  such  proportionate  mixtures  as  are 
required  for  the  degree  of  speed  or  power  desired.  Two  car- 
buretters are  employed,  one  for  each  cylinder.  The  operation  of 


FIG.  247. — Stevens-Duryea  Motor — Pump  Side.  The  spur-gear  water  force 
pump  is  driven  by  sprockets  and  chain  from  the  crank  shaft.  The 
charge  admission  is  throttled  by  moving  the  small  sliding  rod  connected 
to  the  vertical  lever  seen  at  the  right.  This  small  rod,  just  below  the 
mixture  tube,  reaching  horizontally  from  one  cylinder  to  the  other, 
carries  valve  lift  limiting  wedges  at  each  end,  which  permit  greater  or 
less  rise  of  the  automatic  inlet  valves,  according  to  the  wedge  rod  ad- 
justment. The  crank  case  cap  is  secured  by  wing  nuts,  and  can  be 
very  quickly  removed  and  replaced. 

the  throttle  in  each  of  them  is  to  reduce  the  gasoline  aperture  to 
the  required  degree,  both  being  operated  by  the  same  throttle 
lever,  which  connects  to  a  button  coming  through  the  floor  of  the 
carriage  under  the  driver's  foot.  The  ignition  is  by  a  break- 
contact  spark,  the  current  being  generated  by  a  Holtzer-Cabot 
magneto.  By  throttling  the  charge  the  speed  of  the  motor  may 
be  varied  from  200  to  800  revolutions  per  minute. 

As  shown  in  the  photographic  view,  the  cylinders  and  water 
jacket  are  cast  in  one  piece,  the  headplates  being  bolted  over  a 


334 


SELF-PROPELLED    VEHICLES. 


secure  joint.  The  inlet  valves  are  automatic,  while  the  exhaust 
are  operated  from  separate  secondary  camshafts,  by  which  also 
the  make-and-break  of  the  electric  sparking  circuit  is  made  by 
special  rods,  as  shown  in  the  section.  As  may  be  also  seen,  the 
inlet  valves  open  at  right  angles  to  the  exhaust. 

The  Stevens=Duryea  Motor. — Another  engine  of  the  double 
opposed  cylinder  type  is  that  used  on  the  Stevens-Duryea 
carriage.  It  is  in  very  many  respects  a  masterpiece  of  design, 
and  has  shown  high  efficiency  under  operative  conditions ;  com- 
bining lightness  with  power-capacity — the  7  horse-power  engine 


PIG.  248.— Stevens-Duryea  Motor.  Two  opposed  cylinders,  working  on 
cranks  at  180  degrees.  The  crank  shaft  terminates  in  an  integral  disc 
to  which  the  flywheel  is  secured  by  bolts  in  the  outer  circle  of  holes, 
while  the  change-gear  shaft  flange  is  secured  by  bolts  in  the  inner 
circle  of  holes.  Bore,  4^4  inches;  stroke,  4J/2  inches;  compression,  about 
50  pounds;  jump-spark  ignition,  advanced  by  spiral  slot  in  shifting  hub; 
weight  of  motor,  125  pounds  without  flywheel;  weight  of  wheel,  75 
pounds;  cast  iron  cylinders,  aluminum  crank  box  and  cover,  bronze 
plain  bearing  bushes  in  crank  box,  and  bronze  connecting  rods;  maxi- 
mum R.  P.  M.,  675. 

weighs  125  pounds  without  the  75-pound  flywheel,  or  28.57 
pounds  per  horse-power  complete.  As  shown  in  the  accompany- 
ing cuts,  the  cylinders  are  cast  integral  with  their  valve  chambers, 
and  are  bolted  to  the  aluminum  crank  chamber.  The  head  plates 
are  let  into  the  bore  and  secured  with  four  bolts. 

Unlike  the  Haynes-Apperson  motor,  the  Stevens-Duryea  has 
the  two  cylinders  duplicated,  and  so  centred  on  the  crank  case 
as  to  allow  both  exhaust  valves  to  be  operated  from  a  single  cam 
at  the  centre  of  the  camshaft.  Instead  of  throttling  the  car- 
buretter, charge,  as  with  many  other  carriage  motors,  regulation 
is  accomplished  by  an  original  device  for  controlling  the  opening 


GASOLINE    MOTOR    DEVELOPMENT.  335 

of  the  inlet  valves.  A  rod,  connected  between  the  valve  chambers 
of  the  two  cylinders  aaid  separated  by  a  lever  (shown  in  the  cut) 
connected  to  the  top  of  the  single  control  lever,  carries  a  wedge 
arrangement  by  which  the  lift  of  the  valves  may  be  progressively 
limited,  thus  controlling  the  amount  of  fuel  mixture  admitted  to 
the  combustion  chamber  at  any  stroke.  As  may  be  understood, 
both  valves  are  simultaneously  regulated  as  perfectly  as  possible. 
The  water  circulation  is  controlled  by  a  centrifugal  pump  oper- 
ated by  chain  and  sprocket  from  the  main  shaft.  At  the  opposite 
end  of  this  shaft  is  a  disc  having  two  concentric  circles  of  per- 
forations, the  outer  for  securing  flywheel,  the  inner  for  securing 
the  change-gear  shaft,  bolts  being  used  in  both  instances.  Ig- 
nition is  by  jump  spark,  the  circuit  breakers  being  situated  on  the 
two-to-one  shaft,  and  the  regulation  of  the  spark  being  controlled 
from  the  driver's  seat. 

The  most  conspicuous  fact  connected  with  this  motor  is  that 
the  stroke  is  shorter  in  inches  than  the  piston  diameter;  the 
ratio  of  the  two  being  19  to  18.  The  broad  piston  face  yields  a 
high-power  surface,  while  the  compression  is  moderate,  being 
about  50  pounds.  Seven  horse-power  may  be  developed  at  675 
revolutions. 

The  Ford  Motor. — The  Ford  double-opposed  cylinder  motor 
is  one  of  the  few  of  this  type  having  mechanically  operated  inlet 
valves.  The  crank  box  is  covered  by  a  plate,  which  supports  a 
four-lead  oiler  operated  by  crank  chamber  pressure ;  this  oiler  is 
shown  in  working  drawing  detail.  There  is  always  a  small  pres- 
sure in  crank  chamber,  and  this  is  made  to  force  the  lubri- 
cating fluid  through  needle  valves,  which  regulate  a  sight  drop 
through  individual  glass  tubes  for  each  oil  lead.  The  sight  feed 
is  used  for  making  the  original  needle  valve  adjustment  only  for 
each  lead.  The  cylinders  are  closed  at  the  rear  end,  and  the 
water  jacket  covers  only  the  combustion  chamber  and  valve  seats. 
The  second  single  motion  shaft  is  driven  by  gearing  from  the 
crank  shaft,  both  the  admission  and  the  exhaust  valves  being 
mechanically  operated,  only  two  cams  being  used.  The  ignition 
is  by  jump-spark,  from  two  sets  of  batteries,  one  in  reserve,  car- 
ried in  a  tox  fixed  to  the  plane. 

The  motor  sits  on  a  cross  frame  of  its  own,  which  carries  the 
engine,  piping,  tanks  and  speed-change  earn  shaft  all  as  an  in- 


336  SELF-PROPELLED    VEHICLES. 

dependent  entirety,  to  be  secured  to  the  chassis  frame  by  only 
four  bolts,  after  the  motor  passes  the  testing  floor.  The  motor 
piping  is  one  straight  mixture  passage  from  the  carburetter  to 
both  cylinders,  and  one  straight  exhaust  pipe  from  both  cylinders 
to  the  muffler. 

Two  of  the  copper  oil-leads  go  to  the  cylinders,  while  tne  other 
two  are  carried  to  the  crank  shaft  journals  and  the  oiling  func- 
tion is  carried  out  by  establishing  pressure  in  the  crank  chamber 
by  the  application  of  the  starting  crank  to  the  motor  snaft,  and 


FIG.  249.— Section    of    the    Ford    Motor,     showing    positively    operated    inlet 
valves. 

ceases  when  the  crank  chamber  pressure  is  dissipated  by  the 
stoppage  of  the  motor.  This  four-lead  oiler  is  from  original  de- 
signs, and  has  a  large  capacity,  giving  four  independently  regu- 
lated lines  of  lubrication,  besides  being  a  great  saver  of  lubricant. 
The  fuel  mixture  volume  regulation  is  by  treadle  and  rod  and 
bell  crank  and  rod  to  the  rocking  vertical  valve  placed  in  the 
mixture  pascage  from  the  carburetter  to  the  cylinders  The  motor 
action  responds  to  the  fuel  admission,  and  the  spark  advance 
regulation  combined,  or  to  either  one  singly,  the  intelligently 


GASOLINE  MOTOR  DEVELOPMENT.  337 

combined  operation  or  both  being,  of  course,   needful  to  high 
fuel  economy. 

The  Duryea  Three=Cylinder  Motor. — As  the  pioneer  of  the 
three-cylinder  carriage  motor,  the  Duryea  must  be  awarded  a 
conspicuous  position.  .The  claims  of  its  manufacturers — perfect 
balance  of  motion-  and  the  highest  power-output  per  pound 
weight,  while  saving  the  added  complication  of  a  fourth  cylinder 
with  its  necessary  gearing — have  been  amply  justified,  not  only 
by  the  records  of  the  Duryea  carriages,  but  also  by  the  experi- 
ments of  Panhard-Levassor  and  others,  who  have  adopted  this 
type  of  motor.  The  three  cylinders  are  cast  integral,  with  their 


FIG.  250.— The  Duryea  Three-cylinder  10  1-2  B.  H.  P.  Carriage  Motor.  A 
is  the  throttle  slide,  by  which  the  gas  supply  to  the  three  cylinders  may 
be  controlled  by  the  combined  steering  and  control  lever  shown  in  the 
last  figure;  B,  single  wire  connecting  anvils  of  the  three  sparking  plugs 
in  multiple,  the  other  terminal  of  the  circuit  being  connected  to  the 
middle  parts  of  the  cylinder;  C,  the  common  exhaust  tube  conveying 
the  burned-out  gases  to  the  muffler;  D,  the  pipe  conveying  air  to  the 
jackets  of  the  three  cylinders. 

water  jackets  and  valve  chambers,  each  having  a  4l/2  inch  bore 
and  4fi  inch  stroke,  an  output  of  iol/2  B.  H.  P.  being  developed 
at  800  revolutions.  The  three  water  jackets  are  continuous, 
having  common  inlet  and  outlet  ports.  As  will  be  seen  from  the 
sectional  view,  the  jacket  covers  only  the  combustion  space;  the 
object  being  to  cool  only  that  portion  of  the  cylinder  exposed  to 
the  most  intense  heat  of  the  combustion,  leaving  the  remainder  of 
the  sweep  uncooled  in  order  that  the  temperature  may  be  main- 
tained at  as  high  a  point  as  possible  during  the  expansion  of  the 
burned  gases.  The  theory  is  that  too  much  cooling  is  hostile  to 
economy  and  efficiency,  particularly  at  slow  speeds,  and  much  of 


338         .  SELF-PROPELLED   VEHICLES. 

the  wide  range  of  speed  of  the  Duryea  motors  result,  it  is  claimed, 
from  the  fact  that  the  gases  are  not  thus  condensed,  but  remain 
powerfully  expansive  to  the  end  of  the  stroke. 

The  ignition  is  primary  spark,  the  electric  current  being  sup- 
plied by  a  magneto  generator  driven  from  the  flywheel.  One  pole 
is  grounded  on  the  frame  of  the  motor,  while  the  current  from  the 
other  is  carried  bv  two  insulated  anvils  let  into  the  walls  of  the 


FIG.  251.— Sectional  View  through  one  Cylinder  of  the  Duryea  Carriage 
Motor,  showing  working  parts.  The  exhaust  cam  operated  by  a  two- 
to-one  gear  imparts  a  double  motion  to  the  valve  pushrod;  a  lift  for 
opening  the  valve,  and  a  double  twist  for  making  and  breaking  the 
connections  of  the  electrical  spark.  The  valve  and  sparking  chamber 
is  projected  so  as  to  show  the  position  of  contained  mechanism  on  a 
plane  different  from  that  of  the  cylinder  section.  Details  of  the  in- 
sulated sparking  anvil  are  shown  below  the  cylinder.  It  is  an  iron 
contact  point,  having  a  mica  washer  on  the  inside  and  the  outside  of 
the  cylinder  walls,  and  a  mica  bushing  between,  so  as  to  perfectly  in- 
sulate it  from  the  metal  of  the  engine.  A  very  short  water  jacket  and 
the  concave  cylinder  and  piston  heads  are  also  exhibited  in  this  figure. 

combustion  space.  As  shown  in  the  sectional  cut  of  the  engine,  a 
rocking  contact-breaker  or  hammer,  pivoted  in  the  exhaust  valve 
stem  and  caused  to  oscillate  by  a  pawl  extending  over  the  cam- 
shaft, is  lifted  at  the  proper  instant  by  a  cam  shaped  for  the  pur- 
pose. The  lifting  of  the  pawl  brings  the  sparker  hammer  into 
contact  with  the  insulated  anvil,  completing  the  circuit.  The 
sparker  cam  is  abrupt  on  its  rearward  side,  which  permits  the 


GASOLINE  MOTOR  DEVELOPMENT, 


339 


pawl  to  drop  instantly,  making  a  sharp  break  and  producing  a 
strong,  hot  spark.  The  operation  of  the  exhaust  valve  comes  at  a 
different  time,  so  that  the  sparker  operation  is  not  interfered 
with,  while  removing  the  exhaust  valve  likewise  removes  the 
sparker  hammer  and  permits  inspection  when  needed.  The  in- 
sulated anvils  are  connected  in  muliple  to  the  single  wire,  marked 
B  on  the  accompanying  cut.  In  other  particulars,  the  electric  ar- 
rangements are  not  different  from  the  mechanical  generator 
system  long  used  on  the  Mors  carriages. 

The  motor  is  operated  without  governing  mechanism,  the  sole 
regulation  being  a  single  throttle  slide,  marked  A  in  the  Accom- 
panying view  of  the  engine,  by  which  the  amount  o|  opening  of 
the  inlet  valves  may  be  controlled. 


FIG.    252.— Side    Elevation    of    the    Cadillac    Motor,    showing    connections    for 
operating   the   valves   and   speed  gear  on  the  main   shaft. 

The  Cadillac  One=Cylinder  Motor. — The  single-cylinder 
motor  of  the  Cadillac  carriage  embodies  a  number  of  features 
of  exceptional  interest.  Its  high  power  efficiency  may  be  under- 
stood from  the  fact  that  with  a  piston  diameter  and  stroke  length 
each  of  five  inches,  it  develops  6l/2  horse-power  at  800  revolutions, 
and  may  be  speeded  up  as  high  as  8^.  The  cylinder  is  cast 
separate,  the  water-jacket  being  a  copper  sheath,  shaped  and 
flanged  to  be  bolted  over  the  wall,  and  the  valve  chambers  ar- 
ranged to  be  connected  by  a  right-and-left  screw  joint  to  the  head 
of  the  compression  space.  Both  inlet  and  exhaust  valves  are  posi- 


340 


SELF-PROPELLED    VEHICLES. 


tively  operated — the  former  by  a  form  of  walking-beam  from  an 
eccentric,  the  latter  by  a  bell-crank  actuated  by  a  push-rod,  both 
from  the  two-to-one  shaft.  The  eccentric  rod,  C,  controlling  the 


FIG.    253.— Part    Section    of   the   Cadillac    Motor,    showing    position    of   valves 
and  spark  plug  and  the  method  of  securing  the  copper  jacket  cover. 


,/V 


FIG.  254.— Carburetter  and  Intake  Valve  Mechanism  of  the  Cadillac  Motor. 
L  is  the  gasoline  valve;  M,  the  gasoline  inlet;  N,  the  adjusting  screw. 
A  is  the  inlet  valve;  T,  the  walking-beam  for  opening  it  under  positive 
impulse;  C,  the  end  of  the  eccentric  rod,  raising  T  by  bearing  on  roller, 
S,  with  roller,  G,  as  fulcrum.  O  is  the  handle  by  which  the  position  01' 
G,  consequently  the  lift  of  the  valve,  A,  may  be  varied  as  desired. 

inlet  valve,  is  not  attached  direct,  but  operates  as  a  lever  be- 
tween two  rollers,  G  and  S,  as  shown  in  the  sectional  view.  By 
meains  of  the  lever,  O,  connected  by  a  link  to  the  driver's  hand, 


GASOLINE  MOTOR  DEVELOPMENT. 


341 


roller  G,  may  be  shifted  backward  or  forward  along  the  rod  Cf 
thus  altering  the  position  of  the  fulcrum,  and,  with  It,  the  lift  of 
the  walking-beam,  T,  and  the  opening  of  the  valve,  A. 

A  notable  feature  of  this  engine  is  a  peripheral  groove  around 
the  junk  ring  between  the  two  forward  packing  rings  that  con- 
nects with  a  longitudinal  groove  over  the  first  ring.  The  object  of 
the  device  is  to  encircle  the  piston  with  a  ring  of  oil,  ensuring  per- 
fect lubrication  and  utilizing  all  excess  that  might  cause  trouble 
by  igniting. 

This  device  may  be  understood  by  reference  to  Fig.  255,  which 
shows  two  views  of  the  piston  (Figs,  i  and  2).  In  Fig.  i  (bot- 
tom of  piston)  the  junk  rings,  L,  M  and  N,  and  the  first  two 
packing  rings,  A  and  B ,  are  grooved  at  H  and  F,  forming  a  pas- 


M       N    G 


•   FIG.  I.  FIG.  Z. 

FIG.  255.— Diagrams  showing  Oil  Groove  Arrangement  in  the  Cadillac  Piston. 


sage  to  the  circular  groove,  G,  which  continues  aroiind  the  junk 
ring,  N,  connecting  with  the  grooves,  H  and  K  (on  top  of  the 
piston),  Fig.  2,  thus  forming  a  passage  past  the  third  packing 
ring,  C. 

The  result  is,  that  any  excess  of  oil  on  the  lower  part  of  the 
cylinder  wall  is  forced  into  the  circular  groove  around  each  side 
of  the  piston  and  out  on  the  top,  thereby  encircling  the  piston 
with  a  ring  of  oil  in  the  groove,  G. 

The  passage  is  too  small  to  produce  any  loss  of  power  what- 
soever, but  maintains  the  most  perfect  lubrication  possible  at  all 
points  in  the  cylinder,  using  the  oil  that  usually  causes  all  kinds  of 
trouble.  By  use  of  a  convenient  device,  one  key  is  arranged  to 
make  the  battery  circuit  and  to  start  the  feed  of  oil  under  pres- 
sure. 


342  SELF-PROPELLED   VEHICLES. 

The  ignition  is  by  jump-spark,  the  secondary  circuit  being  con- 
ducted to  the  terminals  of  the  double  plug,  already  shown  by 
insulated  cables,  not  grounded,  as  usual  circuits.  The  primary 
is  grounded  to  the  metal  of  the  cylinder.  A  wipe  contact  com- 
mutator is  used. 

The  carburetter  used  \vith  this  motor  is  shown  in  position  in 
Fig  252,  and  in  section  in  Fig.  254.  Air  is  admitted  through 
the  vertical  bent  t::be  at  the  rear  end  of  the  cylinder,  through  a 
cone-shaped  filter  screen.  Under  suction  of  the  piston,  it  causes 
the  valve,  L,  to  rise  more  or  less  from  its  seat  by  pressure  against 
the  wing  flange  carried  on  its  rod,  thus  opening  the  gasoline 
passage,  M,  according  as  its  lift  is  regulated  by  screw,  N.  Va- 

" ~ •  -....,-.., - — 

~****&m^* 


FIG.  256.— The  Olds  Carriage  Motor. 

riations  in  the  speed  of  the  engine  change  the  velocity  of  the 
incoming  air  current,  and  also  the  suction  of  gasoline  at  M,  thus 
automatically  regulating  the  amount  of  gasoline  admitted  with 
the  air  drawn  into  the  tube. 

The  Olds  Motor. — The  motor  used  in  the  runabout  is  of  the 
single-cylinder  four-cycle  type,  having  a  4l/2"  bore  and  a  6" 
stroke,  and  developing  about  4.7  horse  power  at  600  revolutions 
per  minute.  By  a  careful  calculation  of  the  weights  of  rotating 
and  reciprocating  parts,  vibration  has  been  reduced  to  a  minimum. 
The  transmission  gear  is  carried  direct  upon  one  end  of  the  main- 


GASOLINE   MOTOR   DEVELOPMENT. 


34; 


chaft,  just  outside  the  flywheel,  the  other  extremity  carrying  the 
circulating  water  pump,  starting  ratchet  and  spiral  gear — this  lat- 
ter for  actuating  the  cam  shaft.  This  extends  horizontally  to  the 
head  of  the  motor,  where  it  actuates  a  rocking  cam  which  engages 
both  the  inlet  and  exhaust  valve. stems,  these  projecting  below  the 
motor  head.  The  make-and -break  contact  for  the  jump-spark  ig- 


FIG.  257.— Part   Sectional  View  of  the  Olds  Motor,   showing  valve-operating 
mechanism. 


FIG.  257a.— Connecting  Rod  of  the  Olds  Motor,  showing  heavy  construction. 

nition  apparatus  is  also  on  the  cam  shaft,  being  disposed  just  back 
of  the  worm  gear  which  drives  it. 

The  Fuel  Supply  is  drawn  direct  from  fuel  tank  into  removable 
sediment  cup  or  vaporizer ;  all  impurities  being  deposited,  passes 
through  vertical  tube  and  regulating  needle  valve  to  spraying 
nozzle.  Flow  determined  by  a  valve  opening  against  gravity  by 


344 


SELF-PROPELLED   VEHICLES. 


suction  in  the  motor  cylinder.  A  light  collar  or  flange  upon  the 
stem  aids  in  lifting  the  valve  and  in  spraying  the  gasoline  in  the 
path  of  the  inrushing  air,  which,  like  the  gas,  is  under  control  by 
means  of  a  sliding  gate  with  a  slot  just  wide  enough  to  permit  of 
movement  backward  and  forward  across  the  air  passage.  A 
priming  device,  a  small  brass  piece  sliding  on  the  nozzle,  may  be 
lifted  closing  the  gate  valve  opening,  compelling  all  air  to  pass 
through  vertical  holes  drilled  through  it,  so  as  to  strike  the  flange 
on  the  needle  valve  spindle,  lifting  it  from  its  seat.  Thus  the  flow 
of  gasoline  is  kept  normal,  in  spite  of  slow  suction  when  cranking 
the  engine. 


FIG.  258.— The  Olds  Mixer,  with  parts  designated. 


CHAPTER  TWENTY-THREE. 

THE  CONSTRUCTION  AND  CONTROL  OF  TYPICAL  GASOLINE  CARRIAGES. 

Daimler's  Early  Motor  Carriages. — The  first  application  of 
the  Daimler  motor  to  the  work  of  propelling  road  vehicles  was 
made  in  1885,  when  Daimler  built  the  motor  bicycle,  or  velocipede, 
shown  in  an  accompanying  illustration.  The  motor  was  hung  be- 
tween the  wheels  from  a  heavy  iron  framework,  and  directly 
above  it  was  the  seat.  Just  below  the  motor,  and  connected  to  the 


PIG.  259.— Sketch  of  Daimler's  First  Gasoline  Propelled  Bicycle.  This  ma- 
chine is  shown  arranged  for  sliding  on  ice,  having  teeth,  C,  in  the  rear 
wheel-,  and  the  runner,  F,  secured  to  the  forward  wheel,  E.  A  is  the 
driving  pulley  on  the  rear  wheel;  B,  the  cylinder  of  the  motor. 

platform  on  which  it  rested,  were  two  auxiliary  rollers  or  small 
wheels,  which  could  be  drawn  up  or  lowered  by  the  pressure  of 
the  driver's  foot  on  a  pedal.  The  object  of  these  rollers  was  to 
afford  a  support  for  the  vehicle  when  the  motor  was  not  in,  opera- 
tion. 

On  the  earliest  bicycle  of  this  tvpe,  which  saw  its  first  success- 
ful trial  on  November  10,  1885,  the  driving  was  by  a  belt  from 

345 


346  SELF-PROPELLED    VEHICLES. 

a  pulley  carried  on  the  crank-shaft  to  another  one  of  larger 
diameter,  attached  to  the  rear  wheel.  The  motor  was  started 
by  pushing  the  bicycle  in  the  usual  manner,  and  the  power  was 
thrown  in  or  out  by  drawing  up  the  jockey  pulley,  thus  tight- 
ening the  belt.  While  there  were  no  provisions  on  this  bicycle 
for  varying  the  speed  during  travel,  it  was  possible  to  shift  the 
belt  between  two  pulleys  of  different  diameter  attached  to  the 
driving-wheel,  thus  securing  some  slight  variation. 

The  earliest  four-wheeled  vehicle  was  propelled  by  a  Daimler 
upright  single-cylinder  engine,  such  as  has  already  been  de- 
scribed. The  connections  and  manner  of  shifting  the  jockey 


FIG.  260.— The  First  Daimler  Motor  Carriage.  The  motor  was  connected  to 
the  driving  axle  by  two  belts;  one  for  high  speed,  the  other  for  climb- 
ing; either  being  thrown  into  action  as  the  belts  were  tightened  by 
jockey  pulleys,  as  shown  in  Fig.  261.  Both  could  be  thrown  out  of  ac 
tion  to  stop  the  carriage  without  stopping  the  motor.  The  forward  axle 
of  this  carriage  was  centre-pivoted  and  turned  on  a  fifth  wheel,  as  in 
horse  carriages;  the  steering  being  by  upright  pillar  rising  before  the 
driver's  seat. 

pulley  or  idler,  used  for  tightening  the  belt,  are  shown  in  the 
detailed  cut  of  the  motor.  The  belt  transmission  used  on  the 
early  bicycles  is  practically  the  device  used  on  Daimler's  motor 
carriages  for  a  number  of  years.  As  a  matter  of  fact,  numerous 
writers  speak  of  this  form  of  transmission  as  a  typical  feature. 

The  earliest  four-wheeled  vehicle  propelled  by  a  Daimler  motor 
was  built  in  1886.  It  seems  to  have  been  a  modified  horse  car- 
riage, having  the  forward  axle  turned  by  an  upright  steering 


TYPICAL   GASOLINE   CARRIAGES. 


347 


pillar  and  hand-wheel,  and  with  driving  pulleys  geared  to  each 
of  the  rear  wheels.  As  show.n  in  an  illustration,  which  was  re- 
produced from  a  German  book,  a  motor  of  the  same  general 
type  as  that  used  on  the  bicycles  was  placed  behind  the  forward 
seat,  and  imparted  its  power  direct  from  the  main  shaft  to  the 
driving  pulleys  on  the  rear  wheels. 

The    Daimler    Belt    and    Pulley    Transmission. —The    belt 
transmission,  used  with  the  earlier  Daimler  carriages  consisted  of 


FIG.  261.— Diagram  of  the  Belt  Transmission,  used  on  the  early  Daimler 
carriages.  As  shown  in  the  cut,  two  pulleys  of  different  diameters— any 
diameter  ratios  may  be  used— are  connected  by  a  belt.  This  belt  is 
normally  loose,  but  may  be  tightened  by  a  jockey  pulley  mounted  on 
one  arm  of  a  bell  crank  lever,  so  as  to  tighten  or  loosen  the  belt,  ac- 
cording to  the  position  given  it  by  the  hand  lever,  as  indicated  by  the 
full  and  dotted  lines. 


four  pulleys  regularly  increasing  in  size,  keyed  to  the  main  shaft, 
and  four  others  regularly  decreasing  in  size  in  the  same  order, 
keyed  to  the  countershaft.  Four  belts  connected  these  eight 
pulleys,  and  the  power  was  thrown  upon  any  one  pair  as  desired, 
by  tightening  the  belt  with  an  idler  pulley  mounted  on  a  suit- 
ably disposed  bell  crank.  By  this  method  it  was  possible  to  ob- 
tain four  speeds  forward  on  an  even  roadway,  or  to  vary  the 
power  in  ascending  grades.  There  was  no  provision,  however, 
for  reversing,  the  only  method  of  turning  the  carriage  in  a  short 


348 


SELF-PROPELLED   VEHICLES. 


radius  being  to  bring  the  centre  pivoted  front  axle  all  the  way 
around,  so  that  the  small  forward  wheel  cut  under  the  body,  as 
in  a  horse-drawn  vehicle.  It  might  have  been  possible  to  re- 


FIG.  262.— Diagram  of  a  Variable  Cone  Pulley  Transmission,  by  which  the 
relative  speeds  of  the  driving  shaft  and  countershaft  may  be  varied  by 
changing  the  diameters  of  the  driving  and  driven  pulleys.  In  this  figure, 
A  is  a  frame  on  which  are  mounted  two  shafts,  B  and  B,  turning  in  the 
bearings,  C  and  C.  On  each  of  these  shafts  is  a  feather,  D,  on  which  slide 
double  cones,  F,  F,  F,  F.  To  the  apex,  J,  of  each  of  these  cones,  are  at- 
tached fingers,  S,  S,  S,  S,  which  are  screwed  to  the  heads,  G,  U,  U,  <j,  as 
shown.  A  handle,  P,  pivoted  at  N,  may  be  turned  in  either  direction, 
actuating  the  levers,  L,  L,  L,  L  and  K,  K,  K,  K;  thus  modifying  the 
belted  diameter  of  either  pulley  from  that  shown  in  the  upper  of  the 
two  to  that  shown  in  the  lower  one.  Thus  the  speed  ratios  in  the  two 
may  be  varied  to  any  desired  point.  The  levers,  K,  K,  K,  K,  by  forked 
connections,  actuate  the  cones,  causing  them  to  slide  along  the  feathers, 
D,  D,  D,  D,  at  the  spools,  J,  J,  J,  J.  The  device  shown  in  this  illus- 
tration is  the  subject  of  an  American  patent;  but  similarly  arranged 
and  operated  cone  pulleys  have  been  employed  on  the  Fouillarion  car- 
riage and  others. 


verse  by  simply  crossing  one  of  the  belts,  although  it  is  doubtful 
if  a  cross  belt,  unless  of  unusual  length,  could  be  tightened  with 
an  idler  pulley.  A  loose  pulley  on  both  shafts  of  a  belt-shifter 


TYPICAL   GASOLINE  CARRIAGES.  349 

would  seem  to  furnish  the  only  really  practical  device.  Fast  and 
loose  pulleys  with  shifting  belts  have  been  successfully  applied 
in  several  types  of  motor  vehicle,  notably  on  some  of  the  light 
Benz  carriages  made  in  Germany,  and  one  or  two  of  those  manu- 
factured by  the  English  Daimler  Motor  Co.  In  both  these  in- 
stances, however,  the  shafts  are  arranged  at  a  sufficient  distance 
between  centres  to  enable  an  easy  shifting  of  the  belts. 

Typical  Transmission  Systems. — Although,  as  shown  in  the 
foregoing  cuts  of  the  early  Daimler  carriages,  the  original  plan  of 
transmission  was  to  belt  the  main  shaft  to  a  secondary  carry- 
ing a  spur  gear  to  drive  the  road  wheels,  the  belt  and  chain  drive 
soon  became  the  prevailing  type.  This  was  true  even  with  the 
Mors  carriages  having  the  motor  hung  to  the  rear  axle.  .The 
early  Valee  carriages  were  driven  by  a  belt  direct  from  the  main 
motor  shaft  to  the  rear  axle,  the  speed  being  varied  solely  by 
throttling,  without  the  use  of  speed-changers  of  any  kind.  This 
involved  the  use  of  an  extra  high  powered  engine.  The  Darracq- 
Bollee  had  a  stepped  cone  pulley  arrangement  in  which  the  belt 
was  shifted  by  a  special  belt-shipper,  as  in  lathes  and  other  shop 
machinery,  while  several  other  cars  had  only  the  Daimler  belt 
tranmission  already  described.  The  belt,  however,  fell  into  disuse 
on  the  best  makes  of  car,  the  tendency  being  steadily  toward  chain 
or  bevel  gear  transmissions.  Virtually,  only  one  notable  car  uses 
the  belt  at  the  present  time,  and  that  is  the  Fouillarion,  whose 
speed-changer  is  the  variable  pulley  shown  on  the  opposite  page. 
As  regards  direct  bevel  gear  drive  to  the  differential,  that  was 
probably  introduced  on  the  Darracq  carriages,  by  which  it  is  still 
used.  This  arrangement  has  the  advantage  of  a  firm,  steady 
drive,  saving  most  of  the  power  that  is  inevitably  lost  in  chain- 
driving.  Some  builders  object  to  it,  however,  on  the  ground  of 
the  extra  wear  and  looseness  that  follows  on  long  use,  although, 
as  seems  probable,  this  difficulty  may  be  largely  overrated. 

Countershaft  and  Dead  Axle  Transmissions. — At  the  pres- 
ent day  the  typical  French  transmission  is  to  drive  from  the  main 
shaft,  through  the  speed  gear  to  a  countershaft  set  across  the 
width  of  the  carriage.  Sprocket  and  chain  connection  from  either 
extremity  of  this  secondary  shaft  to  both  road  wheels,  turning  on 
a  dead  axle,  drives  the  carriage.  This  arrangement  is  shown  in  the 


350  SELF-PROPELLED    VEHICLES. 

plan  view  of  the  Panhard  six  horse-power  carriage.  The  prevail- 
ing plan  in  American  carriages,  until  within  a  very  few  years,  has 
been  to  drive  direct  from  the  main  shaft,  or  a  secondary,  carrying 
the  speed  gear,  by  chain  and  sprocket  to  the  differential  on  a  live 
rear  axle. 

The  Work  of  Panhard=Levassor  and  Others. — One  of  the 

most  important  chapters  in  the  history  of  gasoline  motor-vehicle 
development  is  to  be  found  in  the  work  of  the  French  firm  of 
Panhard  &  Levassor,  whose  name  is  still  regarded  as  among 
the  foremost  in  the  automobile  world.  This  firm  was  originally 
a  manufacturer  of  various  kinds  of  industrial  machinery,  and 
brought  io  the  manufacture  of  motor  vehicles  a  long  experience 
and  a  well-equipped  plant.  Evidently  foreseeing  the  possibili- 
ties of  the  Daimler  engine  and  carriage,  they,  in  1890,  secured 
the  French  rights  to  manufacture  both.  Thereafter,  for  several 
years,  other  French  manufacturers  of  motor  vehicles  using  the 
Daimler  motors  were  obliged  to  obtain  their  engines  from  Pan- 
hard-Levassor. 

Not  only  are  the  Panhard  vehicles  notable  from  the  fact  that 
they  were  among  the  earliest  successful  carriages,  but  also  be- 
cause, owing  to  the  vast  skill  and  experience  of  their  manufac- 
turers, they  embodied  principles  o<f  design  which  are  recog- 
nized as  the  most  excellent  for  motor  carriage  purposes,  and 
some  of  which  must  certainly  continue  permanent.  Among  these 
excellent  elements  of  construction,  may  be  mentioned  the  fact 
that  from  the  start  they  adopted  a  wooden  underframe,  at  first 
sheathed  with  angle-iron,  later  consisting  of  wooden  bars,  and  at 
no  time  in  the  development  of  their  vehicles  did  they  waste  time 
and  ingenuity  on  the  steel  tubular  framework,  which  many  manu- 
facturers still  seem  to  consider  essential  for  securing  the  com- 
bined ends  of  strength  and  lightness.  Among  the  earliest  known 
examples  of  steel  tubular  construction  was  the  Peugeot-Daimler 
carriage  of  1895. 

The  general  designs  of  Panhard-Levassor  were  adopted  by  the 
English  Daimler  Motor  Co.,  and  also  had  a  great  effect  on  the 
subsequent  construction  of  the  German  manufacturers.  The 
eraliest  types  of  their  carriages,  as  also  manufactured  by  Peugeot 
Brothers  and  the  English  Daimler  Motor  Co.,  were  equipped 
with  the  famous  V-shaped  Daimler  engine,  which  was,  however, 


•  TYPICAL   GASOLINE   CARRIAGES, 

7 


351 


1  ^  IJ.S3  5851*8  §,££g  fa  *  |5  £  ill^^l 


352 


SELF-PROPELLED    VEHICLES. 


of  not  more  than  6  H.  P.  Very  early  in  the  development  of  their 
carriages,  also,  this  firm  devised  and  constructed  the  speed- 
changing  gear,  which  will  be  described  on  a  later  page  under  their 
name.  A  very  similar  structure  was  used  on  the  Peugeot  car- 
riages, the  principal  difference  lying  in  the  fact  that  the  reverse 
motion  was  accomplished  by  throwing  into  gear  an  extra  spur- 
wheel  or  idler,  which  was  of  sufficient  length  along  its  spindle 
to  connect  together  two  spurs  on  the  interacting  shafts,  apart 
from  the  ordinary  process  of  shifting.  The  latter  description  of 


FIG.  265.— Side  Elevation  of  the  Panhard-Levassor  Six-horse-power  Carriage. 
A,  the  transmission  gear  case;  E,  the  gasoline  tank;  H,  oil  pump;  L, 
lever  for  throwing  out  clutch;  L',  reversing  lever;  L",  change-speed 
lever;  M,  starting  crank;  O,  rear  wheel  sprocket;  P'",  sprocket  pinion 
on  jack  shaft;  Q,  driving  chain;  S,  rear  wheel;  S',  forward  wheel;  T,  the 
steering  wheel  and  pillar;  R,  rear  spring;  R',  forward  spring;  1,  male 
cone;  2,  female  cone. 

gear  is  the  same  in  general  principles  as  was  used  on  some  of  the 
later  cars  constructed  by  the  Cannstadt-Dcimler  Co. 

Another  structural  feature  of  the  Panhard  carriages  was,  fol- 
lowing along  the  now  accepted  Daimler  lines,  the  placing  of  the 
motor  over  the  forward  wheels  and  covering  it  by  a  sloping  fore- 
structure  or  bonnet.  With  the  Peugeots,  Benz,  Mors,  De  Dion, 
and  several  other  well-known  designers  and  builders,  the  usual 
plan  was  from  the  start  to  hang  the  motor  over  the  rear  axle,  and 
some  of  the  earlier  carriage  constructions  resulted  in  so  over- 
loading the  rear  wheels,  that,  according  to  some  authorities,  steer- 


TYPICAL   GASOLINE   CARRIAGES.  353 

ing  was  rendered  difficult.  As  the  science  of  vehicle  construction 
developed,  however,  this  difficulty  was  fully  overcome,  and  it  is 
now  a  well-accepted  principle  of  construction  that,  while  the  bulk 
of  the  weight  should  rest  over  the  rear  axle,  the  forward  axle 
should  also  bear  a  large  part  of  the  load. 

The  Panhard  Control  System. — The  Panhard-Levassor  car- 
riage shown  in  accompanying-  cuts  is  typical  of  the  arrangements 
still  used  by  its  manufacturers,  although  in,  the  various  models 
now  made  a  number  of  changes  will  be  discovered.  Whether 
constructed  with  2,  3  or  4  cylinders,  the  motor  is  placed  over  the 
forward  axle,  and  transmits  its  power  through  a  longitudinal 
shaft  and  a  cone  clutch  to  the  change-speed  gear.  Here  the  rota- 
tion is  transferred  by  bevels,  as  shown  in  the  cuts,  to  the  differen- 
tial drum  on  the  transverse  countershaft.  As  the  details  of  the 
motor,  change-speed  gear  and  steering  connections  of  this  make 
of  vehicle  havfe  already  been  explained,  we  may  proceed  to 
examine  the  method  of  control  here  employed.  There  are  three 
levers,  marked  respectively  L,  L/,  L",  by  which  all  the  necessary 
functions  beside  steering — and  in  later  models  throttling  and 
spark  controlling — may  be  perfectly  performed.  As  may  be 
readily  understood,  the  operation  of  the  transmission  gear  of  this 
car,  as  shown  in  Fig.  266,  requires  three  separate  levers — the  one 
for  setting  and  releasing  the  clutch  marked  H  (L)  in  that  figure, 
the  second  D  (L"),  for  sliding  the  gears  upon  the  square  shaft  A, 
and  the  third  (Z/)  for  shifting  either  of  the  bevels  H  or  Z,,  in  or 
out  of  gear  with  bevel  G,  carried  on  the  end  of  secondary  shaft  C, 
thus  affording  means  for  reversing  the  movement  of  the  carriage. 
The  clutch  lever,  £  (L),  if  carried  back  sufficiently  far,  after 
throwing  out  the  clutch,  will  set  the  hub  brakes,  thus  performing 
these  two  necessarily  consecutive  functions  by  one  act  of  the 
chauffeur. 

The  Panhard=Levassor  Speed  Gears. — The  sliding  gear 
transmission  and  reversing  mechanism  used  on  the  earlier  Pan- 
hard  carriages  is  shown  in  an  accompanying  figure.  It  consists 
of  two  shafts,  A  and  C,  the  former  carrying  on  its  square  portion 
the  sleeve,  B,  upon  which  are  four  spur  gears  of  varying  diameter. 
On  the  shaft,  C,  are  keyed  four  gears,  whose  diameters  vary  in- 
versely with  those  on  A.  At  the  right-hand  extremity  of  the 


354 


SELF-PROPELLED    VEHICLES. 


shaft,  A,  is  carried  the  male  cone  of  the  main  clutch,  which,  when 
held  in  gear  by  a  pressure  of  the  spring,  F,  enables  the  trans- 
mission of  power  direct  from  the  crank  to  the  shaft,  A.  -The 
clutch  may  be  thrown  out  by  lever,  £,  which  acts  to  pull  the  shaft, 
A,  to  the  left,  compressing  the  spring,  F.  The  sleeve,  B,  may 


FIG.  266.— Details  of  the  Panhard-Levassor  Change  Speed  Gear.  A  is  a 
square  section  of  the  main  driving  shaft;  B  is  a  sleeve  caused  to  slide 
on  A  by  means*  of  lever,  D,  which  carries  four  spur  pinions,  B1,  B-,  Ba,  B4, 
of  such  diameter  as  to  mesh  with  pinions,  C1,  C2,  C3,  C4,  keyed  on  the 
countershaft,  C;  the  motion  being  imparted  from  the  main  shaft,  A, 
through  sleeve,  B,  through  any  one  pair  of  pinions  to  the  shaft,  C,  caus- 
ing the  rotation  of  the  bevel  pinion,  G.  Gears,  H  and  L,  are  secured  to 
a  sleeve  sliding  on  a  feather  on  shaft,  M.  J  is  a  differential  gear  drum. 
The  main  clutch  is  thrown  on  or  off  by  means  of  the  lever,  E,  and  is 
held  in  position  by  the  spring,  F. 

be  shifted  on  the  main  shaft  by  lever,  D,  which  is  connected  as 
indicated.  When,  as  in  the  cut,  the  gear,  B1,  is  meshed  with  the 
gear,  C1,  the  car  will  have  its  slowest  speed  forward,  and  the  act 
of  shifting  the  gears  to  the  left  from  that  position  will  raise  the 


PICAL   GASOLINE   CARRIAGES. 


356 


SELF-PROPELLED    VEHICLES. 


speed  at  a  regularly  increasing  ratio ;  the  meshing  of  B2  and  C2, 
giving  the  second  speed  forward,  and  the  other  gears  the  next 
two  increasing  speeds.  Similarly,  also,  in  the  act  of  shifting  the 
sleeve  from  the  extreme  left  position,  when  gear,  B4,  is  meshed 
with  gear,  C4,  there  will  be  a  similarly  regular  decrease  of  ratio 
in  their  speed. 

The  motion  is  transmitted  from  shaft,  C,  through  the  bevel 
gear,  G,  which,  as  shown  in  both  sections  of  the  cut,  meshes  with 


FIG.  268.— Sketch  of  the  Improved  Panhard-Levassor  Transmission  and 
Clutch.  Here,  M  is  the  square  portion  of  the  clutch  shaft,  and  N  the 
driving,  or  top,  shaft,  carrying  a  bevel  pinion  meshing  with  another 
single  bevel  on  the  transverse  jack  shaft.  A,  B,  C,  D,  on  the  sleeve 
mesh  with  E,  F,  G,  H,  on  N.  J  and  K  are  gears  keyed  on  a  third 
shaft  parallel  with  M,  shown  projected  at  the  base  of  the  cut.  When 
the  sleeve-carrying  gears,  A,  B,  C,  D,  is  slid  all  the  way  forward  (to 
the  right)  the  third  shaft  is  moved  endwise  against  a  coiled  spring, 
causing  K  to  mesh  with  A  and  J  with  E,  thus  reversing  the  motion  of 
the  carriage.  The  clutch  is  shown  sketched  at  the  left  of  the  cut.  Here 
the  male  cone  is  normally  held  in  by  a  feather  on  the  end  of  a  shaft 
sliding  in  a  longitudinal  bore  in  the  main  shaft,  under  pressure  of  a 
spring.  This  inner  shaft  also  carries  on  its  end  a  two-armed  spider 
with  pins  to  fit  into  holes,  as  shown,  thus  enforcing  the  twisting  resist- 
ance of  the  cone. 

another  bevel  on  the  transverse  jack  shaft.  This  bevel,  H,  and 
a  similar  bevel,  L,  on  the  case  containing  the  differential  gear, 
are  keyed  to  the  sleeve,  M,  which  works  over  the  centre-divided 
countershaft,  at  two  extremities  of  which  are  the  sprocket  pinions 
for  driving  direct  to  each  of  the  rear  wheels.  As  long  as  the 
bevel,  G,  drives  on  H,  as  shown,  the  motion  of  the  carnage  is  for- 
ward, at  any  speed  determined  by  the  relative  position  of  the 


TYPICAL    GASOLINE   CARRIAGES. 


357 


shifting  gears  on  the  two  shafts,  B  and  C.  In  order  to  reverse 
the  motion  of  the  carriage,  the  sleeve,  M,  is  shifted  upon  the 
lever,  acting  on,  the  spool,  K,  so  that  H  is  pushed  out  of  mesh 
with  G,  and  L  is  thrown  in.  By  this  process,  as  is  obvious  al- 
though the  rotation  of  G  continues  in  the  same  direction,  the 
movement  imparted  to  L  will  be  the  reverse  of  that  previously 
imparted  to  H.  Thus  the  reverse  has  the  same  number  of  speed 
and  power  combinations  as  the  forward  motion.  It  is  also  ob- 
vious that,  by  shifting  the  sleeve,  M,  a  certain  distance,  the  driv- 
ing connections  to  the  main  shaft,  through  the  differential,  /, 


FIG.  269.— Two-seated    Pleasur 
Cannstadt-Daimler  Co. 


Carriage    for    General    Use.      Built    by    the 


will  be  thrown  off  altogether.  This  is  the  operation  necessarily 
preceding  the  throwing  on  of  the  brake,  the  drum  of  which  is 
on  the  countershaft,  just  beyond  the  thimble,  H. 

On  the  later  models  of  Panhard  carriages  a  simplified  varia- 
tion of  this  transmission  gear  is  used,  which  drives  through  a 
single  bevel  gear  on  the  jack  shaft,  constantly  in  mesh  with  the 
bevel  on  the  secondary  driven  shaft,  or  top  shaft, — thus  requiring 
no  shifting  of  the  differential  to  throw  in  the  reverse  bevel.  A 
third  shaft,  set  parallel  to  the  clutch  shaft,  carries  two  spur  gears, 
as  shown  in  the  diagram.  The  great  advantage  of  this  arrange- 


358  SELF-PROPELLED    VEHICLES. 

ment  is  that  the  four  forward  speeds  and  reverse  may  be  operated 
with  a  single  lever,  which  may  be  thrown  progressively  forward 
for  each  forward  speed  and  brought  all  the  way  back  for  the  re- 
verse. The  manner  of  operation  is  simple.  The  shifting  lever 
operates  a  rod  sliding  parallel  to  the  three  shafts,  and  from  it  ex- 
tends an  arm  that  engages  the  spool  on  the  sliding  sleeve,  and  also 
slides  along  the  reversing  shaft.  At  the  position  shown  in  the 
diagram  the  lowest  forward  speed  is  engaged,  through  the  mesh- 
ing of  the  spurs,  A  and  £.  By  bringing  the  hand  lever  all  the 
way  back,  the  sleeve  is  moved  clear  to  the  right,  and  A  and  E 
are  thrown  out  of  mesh.  At  the  same  time,  the  arm  of  the  sliding 
gear  shifter  meets  a  raised  portion  of  the  reverse  shaft,  as  shown, 
and  pushes  it  to  the  right,  depressing  the  rpring.  The  spur,  /,  is 
then  meshed  with  £,  and  K  with  H— the  movement  of  the  main 
clutch  shaft  being  thus  transmitted  to  the  top  shaft  through  the 
engagement  and  rotation  of  the  third,  or  reverse,  shaft. 

The  Daimler  Transmission  and  Control — The  Cannstadt- 
Daimler  carriage  performs  these  four  functions  by  the  use  of  only 
two  levers — the  one  for  controlling  the  clutch,  changing  the  speed 
and  reversing  the  direction  of  travel ;  the  other  for  setting  and  re- 
leasing the  brakes.  In  the  accompanying  representation  of  this 
carriage,  the  common  clutch  ard  speed  lever  is  seen  beside  the 
seat  to  the  rear  of  and  crossing  the  brake  lever  set  forward 
directly  over  the  driving  sprocket  on  the  end  of  the  transverse 
countershaft.  The  method  of  operating  the  common  change- 
speed  and  reversing  lever  is  found  in  the  use  of  a  double  H- 
shaped  slot,  or  grid  sector,  so  that  the  lever  may  be  moved  back- 
ward or  forward  in  any  one  of  three  parallel  channels,  or  shifted 
sideways  from  one  to  another  by  means  of  a  fourth  channel  cut  at 
right  angles  to  the  other  three,  like  the  cross  line  of  the  letter  H. 

The  theory  and  operation  are  sinpple.  The  hand  lever  is  pivoted 
to  a  cross  spindle,  which  may  be  slid  lengthwise  in  its  bearings 
whenever  the  hand  lever  is  brought  to  the  middle  transverse  slot 
of  the  grid  sector,  thus  providing  the  neceosa.ry  first  principles  for 
operating  the  apparatus.  The  four  speed  and  reverse  gear  is  of 
the  sliding  spur  pattern,  like  the  Panhard-Levassor  already  des- 
cribed, except  for  the  fact  that  the  four  sliding  spurs  on  the  square 
section  of  the  main  shaft  are  in  two  sections  of  two  spurs  each. 
Each  section  is  shifted  by  an  arm  projecting  downward  from  a 


TYPICAL   GASOLINE- CARRIAGES. 


359 


horizontal  rod  bearing  a  rack  on  the  outer  end.  Further- 
more, these  two  rack  rods  are  set  side  by  side,  so  that  a  toothed 
sector  on  the  lower  extremity  of  the  hand  lever  may  engage  either 
one  of  the  racks,  operating  eith'er  of  the  two  lower  speeds  when 
the  lever  is  moving  in  the  left-hand  slot,  and  either  of  the  two 
higher  speeds  when  it  is  moving  in  the  second  slot.  When  drawn 


FIG.  270. — Transmission  Gear  of  the  Cannstaut-Daimler  Carriage  shown  in 
the  last  figure.  Here,  A  is  the  hand  lever;  B,  the  gridiron  quadrant;  C, 
a  dog  on  the  lever  for  throwing  out  the  clutch  in  shifting  the  gears; 
E,  toothed  sector  at  end  of  A  for  actuating  rack  rods  D  and  F  (see  next 
figure);  G  and  H,  low-speed  gears  on  the  clutch  shaft;  J  and  K,  low- 
speed  gears  on  the  second,  or  driving,  shaft;  N  and  O,  high-speed  gears 
on  the  clutch  shaft;  L  and  M,  high-speed  gears  on  the  second  shaft.  H 
and  G  are  shifted  on  square  portion  of  shaft  by  rack,  F;  N  and  O  by 
rack,  D. 

to  the  backward  position  in  either  slot,  it  operates  the  lower  of  the 
two  speeds,  and,  in  the  forward  position,  the  higher  of  the  two. 
In  order  to  reverse  the  movement  of  the  carriage,  the  hand  lever 
is  brought  to  the  mid-position  on  the  grid-sector,  shifted  all  the 
way  to  the  right,  and  moved  forward.  This  operation  is  possible 
because  the  cross  spindle  to  which  the  lever  is  pivoted  carries  an 


360 


SELF-PROPELLED    VEHICLES. 


arm  projecting1  downward  at  right  angles,  and  terminating  in 
another  toothed  sector  that,  when  the  lever  is  slid  over  to  the 
right,  as  just  explained,  engages  a  third  rack  bar  geared  to  throw 
in  the  reverse  pinion,  B  (Fig.  271).  The  arm,  K,  in  the  same 
figure,  carries  an  upward  turned  slot  in  a  position  to  engage  a 
pin  on  the  reverse  rack-shaft,  so  that,  when  that  shaft  is  slid  for- 
ward by  the  interworking  of  the  rack  and  sector,  the  arm  is  lifted 
and  pinion  B  brought  into  position  by  the  operation  of  a  bell- 
crank.  In  addition  to  the  toothed  sector  set  at  its  lower  extremity, 
the  hand  lever  has  an  arm  at  right  angles  exactly  at  the  pivotal 


FIG.  271.— Details  of  Side-shifting  Change  Lever  of  the  Cannstadt-Daimler 
Car.  A  is  the  lever,  pivoted  between  bearings,  B  and  C.  D  is  the  toothed 
sector,  which  may  be  shifted  to  engage  either  of  the  rack  rods,  E  or  F; 
L  is  a  downward  extension  from  the  pivot  rod  of  A,  carrying  the  sector, 
G,  which  may  be  slid  into  mesh  with  rack,  H.  By  sliding  rack,  H,  to 
the  right,  as  in  the  cut,  pin,  J,  lifts  the  rod  attached  to  the  curved  slot, 
K,  throwing  in  the  reverse  pinion.  The  manner  of  doing  this  is  shown 
with  the  pinions,  A  and  C,  meshing  with  the  long  reverse  pinion,  B. 

point,  so  that,  when  the  lever  is  brought  to  the  transverse  slot  of 
the  grid-sector,  this  arm  presses  upon  a  bar,  thus  throwing  out  the 
clutch.  The  advantage  of  this  arrangement  is  that  the  clutch  may 
be  thrown  out  before  the  gears  are  shifted,  without  the  use  of  a 
separate  lever  or  any  locking  device  to  prevent  shifting  of  speed 
before  the  clutch  is  out.  It  has  the  disadvantage,  however,  that 
the  clutch  is  nominally  on,  which  involves  that  a  certain  amount  of 
strength  should  be  required  to  operate  the  lever,  and  thus  prevent 
inopportune  starting  of  the  carriage. 


TYPICAL   GASOLINE   CARRIAGES.  361 

The  Decauville  Carriage. — Next  to  the  Panhard-Levassor, 
the  French  carriage  best  known  in  America,  is  probably  the  De- 
cauville. It  combines  a  number  of  excellent  features,  which  in- 
sure strength  of  construction  and  ease  of  operation.  Like  many 
other  prominent  automobiles,  its  under  frame  is  composed  of 
solid  angle-steel,  to  which  the  front  and  rear  axles  are  hung  by 
springs.  The  drive  is  by  bevel  gear  to  the  differential  drum, 
and  the  two  portions  of  the  divided  rear  axle  turn  in  sleeves, 
which  are  solidly  bolted  to  the  differential  case  and  supported  by 
struts  at  either  side.  The  construction  of  the  running  gear  is 
rendered  still  more  substantial  by  a  solid-pressed  steel  pan  hung 
upon  the  frame,  and  so  shaped  as  to  afford  perfect  support  for 
the  motor  and  transmission  gear  case.  This  arrangement  in- 


FIG.    272.— Decauville   Four-cylinaer   Car,    with   Plain   Tonneau   Body. 

volves  the  further  advantage  of  providing  a  perfectly  rigid  con- 
nection between  motor  and  transmission  when  the  clutch  is  on. 

The  Motor  and  Sparking  Apparatus. — The  1904  models  of 
Decauville  cars  include  one  two-cylinder,  4.29x4.29  inches,  12  to 
15  horse  power,  and  four  four-cylinder  models — 3.5x4.29  inches, 
12  to  16  horse  power;  3.7x4.29  inches,  16  to  18  horse  power; 
3.9x4.29  inches,  18  to  24  horse  power;  5.46x6.43  inches,  40  to 
50  horse  power.  The  first  model  has  a  speed  range  of  between 
8  and  34  miles  per  hour,  the  others  have  a  maximum  speed 
range  of  between  35  and  70.  Like  other  typical  French  motors 
at  the  present  day,  the  inlet  valves  are  mechanically  operated 
from  a  two-to-one  shaft  on  the  opposite  sides  of  the  cylinders 


SELF-PROPELLED    VEHICLES. 


TYPICAL   GASOLINE   CARRIAGES. 


363 


from  the  exhausts.  Ignition  is  by  jump-spark,  which  may  be 
advanced  or  retarded,  on  the  commutator  by  a  handle  operating 
a  rod  set  at  one  side  of  the  steering  pillar.  The  intake  volume 
is  regulated  by  an  automatic  governor,  and  may  also  be  con- 
trolled by  a  handle  at  the  steering  pillar. 

Current  for  ignition  is  supplied  at  the  start  by  storage  batteries, 
which  continue  the  supply  until  a  speed  of  600  revolutions  is 


FIGS.  274,   275.— Side    Elevation    and    Plan    of    the    Decauville    Car,   showing 
working  parts  in  position. 

reached,  after  which  point  the  dynamo  is  automatically  cut  into 
circuit,  and  supplies  sufficient  energy  to  recharge  the  accumula- 
tors and  spark  the  engines. 

The  regulation  is  effected  in  the  following  manner :  When  the 
motor  reaches  a  speed  of  600  revolutions  per  minute,  the  circuit 


364: 


SELF-PROPELLED   VEHICLES. 


TYPICAL   GASOLINE   CARRIAGES. 


365 


breaker  cuts  the  dynamo  into  the  circuit;  from  this  speed  up- 
ward, the  output  of  the  dynamo  remains  practically  constant,  by 
means  of  the  special  winding  employed.  There  is  consequently 
no  particular  precaution  to  be  observed,  no  switch  or  circuit 
changer  or  commutator  to  handle,  and  no  danger  of  failure  to 
operate. 

The  Transmission  Gear. — .The  transmission  gear  is  typical 
for  many  French  and  American  carriages,  being  very  nearly  the 
simplest  device  of  the  kind  at  present  on  the  market.  As  shown 


FIG.  277.— Diagram  of  the  Decauville  Transmission  Gear.  A  is  the  spur 
pinion  at  the  end  of  the  clutch  shaft;  B  and  C,  spurs  on  the  sliding 
sleeve;  D,  E,  F,  G,  spurs  keyed  to  the  second  motion  shaft;  H,  the  re- 
verse pinion,  constantly  in  mesh  with  G,  and  giving  the  reverse,  when 
in  mesh  with  C  also;  K,  the  square  portion  of  the  drive  shaft;  L,  portion 
of  same  journaled  into  the  clutch  shaft. 

in  the  accompanying  sectional  diagram,  it  consists  essentially  of 
two  parallel  shafts.  Of  these,  the  countershaft  carries  four  keyed 
spurs,  the  largest  of  which  is  constantly  in  mesh,  with  the  pinion 
on  the  clutch  shaft,  thus  insuring  a  constant  drive  of  the  counter- 
shaft. As  may  be  seen,  however,  the  clutch  shaft  terminates 
with  this  constantly  meshed  spur,  being  bored  longitudinally,  so 
as  to. afford  a  bearing  for  one  end  of  a  second  shaft,  arranged 
continuous  with  it,  but  turning  separately.  The  entire  length 
of  this  second  shaft  between  bearings  is  of  square  section,  so 
that  a  double-faced  pinion  may  be  slid  from  end  to  end  by  means 
of  a  fork  set  at  one  end  of  the  gear-shifting  lever. 


366 


SELF-PROPELLED    VEHICLES. 


The  operation  is  readily  understood:  When  the  gears  are  in 
the  neutral  position  shown  in  the  diagram,  the  clutch-shaft  pinion 
drives  the  countershaft,  without  transmitting  motion  to  the  road 
wheels.  When  the  double-faced  gear  is  moved  to  the  left,  so 
that  the  second  small  pinion  on  the  countershaft  meshes  with 
the  larger  of  the  two  on  the  square  shaft,  the  low  speed  forward 
is  obtained.  By  sliding  the  sleeve  to  the  right,  so  as  to  bring  the 
larger  countershaft  gear  into  mesh  with  the  smaller  one  on  the 
square  shaft,  the  second  speed  is  attained.  By  sliding  the  sleeve 
all  the  way  to  the  right,  so  that,  by  a  form  of  claw  clutch  its  right- 
hand  gear  grips  the  pinion  on  the  clutch  shaft,  the  highest  for- 
ward speed  is  obtained,  the  drive  being  then  continuous  from 


FIG.   278.— Decauville  Car,   with   Side   Entrance   Double   Phaeton   Body. 

the  motor  to  the  road  wheels.  The  reverse  is  obtained  when  the 
sliding  sleeve  gears  are  moved  all  the  way  to  the  left,  so  that 
the  larger  of  the  two  meshes  with  an  idler  pinion,  constantly 
driven  from  the  end  gear  of  the  countershaft,  by  which  means 
the  rotation  of  the  square  section  shaft,  and  of  the  road  wheels  is 
reversed. 


Brakes  and  Control. — Like  other  standard  French  cars,  the 
Decauville  has  two  sets  of  brakes.  The  first,  worked  from  the 
upright  push  pedal  to  the  right  of  the  steering  pillar,  is  a  band 
clutch  on  a  drum  just  to  the  rear  of  the  transmission  gear  case. 
The  second  brake,  consisting  of  the  usual  compression  bands  on 


TYPICAL   GASOLINE   CARRIAGES. 


367 


each  of  the  rear  wheel  hubs,  is  operated  by  a  hand  lever  at 
the  right  of  the  driver's  seat,  outside  of  the  change-speed  lever. 
It  normally  stands  upright,  as  shown  in  the  cut,  and  is  thrust 
forward  in  the  act  of  setting  the  brakes.  Except  for  the  fact 
that  the  pedals  are  upright  and  are  operated  by  pushing  for- 
ward, instead  of  by  being  depressed,  the  control  system  is  very 
similar  to  that  shown  in  the  cut  of  the  Locomobile  operating 
devices. 


FIG.    279.— The   Winton   Two-cylinder   Tonneau   Car. 

The  Winton  Gasdfirie  Carriage. — The  well-known  Winton 
carriage,  formerly  built  \vith  a  single-cylinder  motor,  but  now,  in 
some  models,  with  a  double  opposed  cylinder,  embodies  many  ex- 
cellent features.  The  front  and  rear  axles  are  connected  by  two 
reach  rods  arranged  to  form  a  triangle,  whose  apex  touches  the 
centre  of  the  forward  axle,  where  a  swivel  joint. is  made,  giving 
the  required  flexibility  on  uneven  roads.  The  body  frame,  resting 
above  the  springs,  is  constructed  of  seasoned  oak,  joined  at  the 
corners  by  iron  angle  pieces.  The  adjustment  of  the  transmission 
is  regulated  by  two  distance  rods,  one  at  either  side  of  the  carriage, 
between  the  body  and  the  running  gear. 


368  SELF-PROPELLED   VEHICLES. 

The  driving  connections  are  direct  from  the  sprocket,  keyed  to 
a  sleeve  on  the  main  shaft,  to  another  sprocket  on  the  differential 
gear  drum  on  the  rear  axle.  The  operations  of  throwing  on  the 
power  and  changing  the  speed  is  accomplished  by  two  friction 
clutches,  while  the  reverse  is  obtained  by  a  third  clutch,  as  pres- 
ently shown.  The  control  of  this  apparatus  is  by  means  of  two 
levers  rising  to  the  right  hand  of  the  driver.  The  longer  of  these 


FIG.  280.— Winton  Pedals  and  Levers,  foot  board  removed.  B,  outside  hand 
lever,  pulled  to  backward  extreme  clutches  high  speed  into  action,  idle 
in  mid-position,  forward  extreme,  applies  emergency  brake  to  motor 
shaft  brake  drum.  C,  inside  hand  lever,  forward  extreme,  engages  back- 
ing gear,  rear  extreme,  engages  slow  forward  speed.  D,  compressed  air 
release,  pedal  motor  control.  E,  rear  wheel  brake  treadle,  retained  by- 
ratchet,  El.  F,  spark  advance,  retained  by  notched  quadrant.  G, 
muffler  regulation.  H,  battery  switch. 

two,  when  drawn  back,  connects  the  driving  gear  and  motor,  and, 
when  shifted  all  the  way  forward,  applies  a  powerful  brake  to  the 
differential  drum.  The  shorter  of  the  two  levers  operates  the 
speed  changing  and  reverse  gear ;  one  pull  back  throwing  in  the 
reduced  or  hill-climbing  gear,  and  one  pull  forward  engaging  the 
reverse. 


TYPICAL   GASOLINE   CARRIAGES. 


369 


In  addition  to  the  brake,  already  mentioned,  there  is  a  special 
emergency  brake,  operated  by  a  foot  pedal,  which  is  to  be  used 
only  when  the  lever  fails  to  operate.  The  steering  in  the  latest 
models  is  controlled  by  a  hand-wheel  actuating  an  irreversible 
worm  gear,  somewhat  after  the  design  of  the  Panhard  carriages, 
as  shown  in  Fig.  48. 

The  Winton  Motor  and  Attachments. — The  Winton  motor 
is  conspicuous  for  combining  several  excellent  features  of  con- 
struction and  operation.  The  two  cylinders  are  cast  and  bored 


H 


FIG.  281.— Sectional  Diagram  of  the  Winton  Two-cylinder  Motor  and  Parts. 
A,  exhaust  valve;  B,  pipe  leading  exhaust  gases  to  muffler;  C,  exhaust 
valve  spring;  D,  set  screw;  E,  roller  engaging  cam,  F,  which  also  en- 
gages with  roller,  G,  and  operates  oil  pump  piston,  H;  K,  filter  for  oil 
forced  from  pump;  L,  ball  valve  on  oil  pump;  M,  by-pass  for  excess  of 
oil  from  pump;  N,  primary  wire  from  coil  to  breaker  box;  O,  spark  cam; 
P,  contact  adjusting  screw;  R,  vertical  pipe  for  oil  forced  from  pump; 
S,  oil  conduit  and  adjusting  screws  to  regulate  flow  of  parts;  W,  pin 
projecting  from  float  in  carburetter.  This  cut  also  shows  the  shape  and 
position  of  the  carburetters,  of  the  inlet  valve  air-line  relief  pipe,  and 
the  sparking  plug.  The  hand  wheels  and  spindles  rising  from  the  car- 
buretters serve  to  regulate  the  maximum  output  of  gasoline  at  each 
suction  stroke. 


separate,  without  jackets,  thus  enabling  a  thorough  hydraulic  test 
for  discovering  any  possible  leaks.  The  cylinders  are  bolted  end 
to  end  through  flat  extensions  cast  on  one  side.  Both  ends  of 
the  cylinder  castings  are  formed  as  square  flanges,  and  between 
these  aluminum  plates  are  screwed  to  form  the  water  jackets. 
By  this  arrangement  the  exhaust  valve  stems  and  chambers  are 
entirely  surrounded  by  the  circulating  water,  being  thus  perfectly 
cooled. 

As  shown  in  the  sectional  view  of  this  motor,  the  exhaust  valves 
and    sparking   commutator   are   operated    from    the    two-to-one 


370 


SELF-PROPELLED   VEHICLES. 


TYPICAL   GASOLINE   CARRIAGES. 


371 


shafts,  as  is  also  the  oil  pump,  for  distributing  lubricant  to  all 
the  bearings.  This  oil  pump  consists  of  a  plunger  held  in  normal 
position  by  a  spring  and  actuated  by  the  exhaust-lifting  cam. 


AIR  COMPRESSER- 


FIG.  283.— Diagrammatic  Sketch  of  Winton's  Carburetter  and  Intake  Valve 
Action.  The  air  compressor  piston,  P,  is  driven  directly  from  one  of  the 
motor  pistons,  and  forces  air  past  the  check  valve,  V,  into  the  com- 
pressed air  cylinder,  where  it  operates  to  hold  the  piston  to  the  left,  and 
keeps  the  intaking  valve  closed,  regardless  of  the  piston  suction  tending 
to  open  the  valve  by  moving  it  to  the  right.  By  means  of  the  regulating 
cock  the  pressure  may  be  reduced  in  the  air  cylinder,  thus  permitting 
the  intake  valve  to  open,  more  or  less  as  the  air  pressure  is  more  or 
less  reduced  in  the  cylinder.  The  needle  valve,  N,  is  seated  in  and 
carried  by  the  intake  valve  stem,  is  spring  pressed  to  the  left  by  a  coiled 
spring  at  its  right  end,  is  retained  by  a  cross  pin,  S,  and  co-acts  with 
the  adjustable  seat,  A,  S,  to  close  or  open  the  passage  of  gasoline  from 
the  float  chamber  to  the  carburetter  underneath,  whence  the  mixture 
is  drawn  to  the  cylinder  through  the  intake  valve.  No  gasoline  can  go 
to  the  carburetter  without  the  motor  piston  is  moved,  and  more  or  less 
gasoline  goes  to  the  carburetter  as  the  intake  valve  is  lifted  more  or 
less.  The  regulating  cock  governs  the  action  of  the  motor  by  determin- 
ing the  amount  of  air  that  is  allowed  to  escape  through  the  vent.  It 
corresponds  to  the  set  governor  valve  (7)  in  the  previous  figure.  This 
cut,  reproduced  by  courtesy  of  the  "Automobile  Trade  Journal,"  shows 
only  the  theory,  not  the  exact  arrangement  of  the  parts. 


The  oil  forced  by  the  plunger  passes  through  a  filter  and  ball 
valve,  upward  to  the  distributing  chamber  at  the  top  of  the  cylin- 
der, whence  it  is  distributed,  under  pressure,  to  the  bearings, 


372  SELF-PROPELLED    VEHICLES. 

through  the  system  of  tubing  shown  in  the  plan  view  of  the 
engine  and  carriage.  Any  excess  of  oil  is  carried  off  through  a 
by-pass  valve,  thus  preventing  flooding  of  the  bearings. 

The  Winton  Control  System. — The  most  conspicuous  feature 
of  the  Winton  carriage  is  the  pneumatic  control  system,  already 
described  in  diagram  in  the  preceding  chapter.  The  Winton  sys- 
tem throttles  the  quantity  of  the  mixture,  the  quality  remaining 
always  uniform.  The  throttle  is  actuated  automatically  by  air 
pressure,  produced  by  a  small  plunger  pump  at  A,  secured  to  the 
rear  end  of  the  crank  chamber  and  extending  parallel  with  the 
rear  cylinder.  The  pump  piston  is  connected  to  the  piston  in  the 
forward  engine  cylinder  by  a  connecting  rod,  and  the  air  pump, 
therefore,  makes  the  same  number  of  strokes  per  minute  as  either 
of  the  engine  pistons,  and  each  of  its  delivery  strokes  corre- 
sponds in  time  with  a  suction  stroke  of  the  engine.  The  pump 
draws  warm  air  from  the  crank  pit  and  delivers  it  into  a  pipe 
line,  C  C  C,  leading  to  the  two  inlet  valves,  B.  From  this  pipe 
line  another  line,  D,  extends  to  the  escape  valves,  7  and  8.  It  is 
only  through  these  valves  that  the  air  can  escape.  Valve,  7,  is 
the  "set  governor"  for  regulating  the  amount  of  fuel  taken  at 
even  running,  when  the  accelerator  button,  8,  is  not  depressed, 
and  thus  predetermines  the  maximum  effect  of  the  motor.  It 
is  operated  by  means  of  a  dial  lever  at  the  side  of  the  seat.  Valve, 
8,  is  operated  by  means  of  a  foot  button  under  the  operator's  right 
foot.  A  spring  holds  the  foot  button  valve  on  its  seat  when 
there  is  no  foot  pressure  against  it. 

On  the  inlet  valve  in  the  carburetter  is  a  small  plunger,  fitting 
into  the  cylinder  to  the  right  of  spring,  S,  in  the  section  of  the 
carburetter,  and  between  it  and  the  inlet  valve  is  a  bushing  that 
acts  as  a  stuffing  box.  The  air  pressure  leads  to  this  small  cylin- 
der, and  unless  the  pressure  is  relieved  by  opening  either  of  the 
valves,  7  or  8,  there  is  no  chance  for  the  inlet  valve  to  unset  and 
admit  to  the  engine  cylinder  a  charge  of  gas.  On  the  extremity 
of  the  inlet  valve  is  placed  a  conical  needle  valve,  the  taper  of 
which  is  so  proportioned  that  a  lift  of  the  inlet  valve,  allowing 
a  certain  volume  of  air  to  pass  into  the  carburetter,  will  unseat 
the  needle  valve  to  admit  into  the  carburetter  a  proper  quantity 
of  gasoline  which,  vaporizing  and  mixing  with  the  air,  produces 
the  correct  explosive  mixture ;  consequently,  no  matter  how  great 


TYPICAL   GASOLINE   CARRIAGES.  373 

or  small  the  charge  entering  the  cylinder,  the  quality  remains 
uniform. 

With  the  air  line  entirely  closed,  the  inlet  valve  cannot  lift  be- 
cause of  the  air  pressure  against  the  plunger  in  the  small  cylin- 
der. On  relieving  the  air  pressure  by  opening  either  or  both  of 
the  escape  valves,  7  and  8,  the  pressure  exerted  on  the  plunger  is 
relieved  so  that  the  inlet  valve  may  lift  correspondingly.  The 
engine  then  draws  a  proportionate  supply  of  mixture  and  reaches 
a  relative  speed.  By  pressing  upon  the  foot  button,  the  operator 
may  relieve  the  air  pressure  by  minute  degrees  from  the  entirely 
closed  point  to  a  point  where  the  pressure  in  the  air  line  is  no 
greater  than  that  of  non-compressed  air,  so  that  the  Winton 
motor  is  governed  with  extreme  flexibility. 

The  air  line  may  also  serve  as  an  automatic  governor  even  if 
the  air  relief,  7,  is  but  partially  open  and  that  the  motor  tempo- 
rarily tends  to  increase  in  speed ;  the  air  pump,  being  attached 
to  the  piston,  increases  speed  in  the  same  proportion,  and  the  air 
pressure  is  higher  in  the  line  because  the  area  of  the  air  relief  has 
not  been  increased  though  the  pump  speed  has.  With  the  pres- 
sure increased  on  this  inlet  plunger,  the  valve  will  not  lift  as 
high,  and  throttles,  thus  bringing  down  the  speed  of  the  motor. 

Assume  the  motor  tendency  to  decrease  in  speed.  The  pres- 
sure in  the  air  line  will  decrease  because  the  pump  is  not  work- 
ing as  fast  as  before,  and  because  the  relief  opening  has  remained 
unchanged.  As  a  result,  the  inlet  valve  will  lift  higher,  allowing 
a  greater  charge  to  enter  the  cylinder,  which  will  immediately 
accelerate  the  speed. 

The  Winton  Transmission  Gear. — The  Winton  change-speed 
gear,  by  the  use  of  three  pairs  of  interlocking  spurs  and  three 
friction  clutches  of  familiar  type,  can  give  two  forward  speeds 
and  a  reverse.  The  main  shaft  carries  two  spur  wheels,  A  and 
B,  keyed  in  the  positions  shown,  and  a  sleeve  carrying  the 
sprocket,  C,  and  the  spur  wheel,  D.  The  counter-shaft  has  spur, 
L,  keyed  to  it,  and  spurs,  K,  and  N,  turning  loosely  until  clutch, 
H  or  M,  is  thrown  in.  The  main  shaft  and  the  sleeve  are  caused 
to  rotate  together  through  the  contact  surfaces  of  the  friction 
clutch,  £.  To  obtain  the  slow  speed  forward,  the  clutch,  F,  is 
thrown  on  by  shifting  the  thimble,  G,  thus  bringing  the  sleeve, 
carrying  the  sprocket,  C,  and  the  gear,  D,  into  operative  relations 


374 


SELF-PROPELLED    VEHICLES. 


with  the  main  shaft  through  the  friction  clutch,  E.  The  second 
speed  forward  may  be  obtained  by  throwing  in  clutch,  H,  by  slid- 
ing the  thimble,  /,  and  power  is  then  transmitted  from  the  gear, 
A,  which  is  fast  on  the  main  shaft,  through  K  and  L  on  the 
countershaft  to  spur,  D,  which  is  screwed  to  the  sleeve  on  the 


FIG.  284.— The  Winton  Change  Speed  and  Reversing  Gear.  A  and  B  are 
spur  gears  keyed  to  the  crank  shaft  of  the  motor.  C  is  a  sprocket,  and 
D  a  gear,  of  one  piece  with  it,  which  turn  loose  on  the  main  shaft.  E 
and  E'  are  friction  discs,  which  connect  C  and  D  to  the  main  shaft  when 
the  clutch,  G,  is  thrown  in.  K  and  N  are  spur  gears  loose  on  the  coun- 
tershaft, and  meshing  with  A  and  B,  as  shown.  When  clutch,  G,  is 
thrown  in,  the  first  speed  forward  is  obtained;  when  clutch,  H,  is  thrown 
in,  the  second  speed  forward;  and  when  clutch,  M,  is  thrown  in,  the 
reverse.  The  clutches,  H  and  M,  are  operated  by  a  lever  actuating 
spool,  J.  P  is  an  idler  pinion  reversing  the  motion  transmitted  from  B 
to  N.  Q  is  the  fly-wheel  of  the  engine;  L,  a  gear  transmitting  motion 
from  the  countershaft  to  the  sprocket;  and  R,  the  brake  drum. 

main  shaft,  in  rigid  relation  with  the  sprocket,  C.  Similarly,  the 
reverse  movement  is  obtained  by  throwing  on  the  clutch,  M,  by 
sliding  the  thimble,  /,  in  the  opposite  direction,  with  the  result 
that  the  motion  is  transmitted  from  the  main  shaft  to  gear,  B,  to 


TYPICAL  GASOLINE  CARRIAGES. 


3T5 


gear,  Nf  through  the  intermediate  idler  gear,  P,  to  the  counter- 
shaft, and  thus,  through  L  and  D,  to  sprocket  C. 

The  operation  of  this  gear  involves  the  use  of  two  levers — one 
for  throwing  clutch,  G,  and  operating  the  band  brake  on  drum,  R, 
the  other  for  throwing  clutches,  H  and  M. 

The  Winton  Racer. — The  name  of  Winton  is  associated  with 
several  of  the  fastest  racing  cars  that  have  been  built  in  the  United 
States,  notable  among  which  is  the  Winton  "Bullet,"  shown  in 
an  accompanying  illustration.  This  carriage  has  an  eight-cylin- 


BIG.    285.— The   Winton    Racing   Car,    "Bullet,    No.    2." 

der  motor  placed  transversely  in  the  frame,  and  consisting  of  two 
units  of  four  cylinders  each,  connected  by  means  of  a  universal 
flexible  joint.  In  size  and  mehanism  each  cylinder  is  a  duplicate 
of  the  Winton  Touring  Car  motor  construction.  One  carburetter 
supplies  the  mixture  for  each  unit  of  cylinders,  and  only  one  coil 
is  used  for  igniting ;  the  current  passing  to  the  new  Winton  type 
of  distributor,  from  which  it  is  commutated  to  each  separate 
cylinder.  A  positively  operated,  internally-expanding  clutch 
transmits  the  power  to  the  longitudinal  telescopic  universal  drive 


376  SELF-PROPELLED    VEHICLES. 

shaft  through  bevel  gear  connection  to  the  differential  case.  The 
rear  axle  is  equipped  with  adjustable  ball  bearings  throughout. 
There  is  no  change  speed  gear  in  the  system ;  the  high  power  de- 
veloped by  the  motor  in  combination  with  the  Winton  system  of 
air  governing,  and  the  peculiar  pattern  of  clutch  makes  it  possi- 
ble to  pick  up  speed  gradually,  and  without  jerking,  on  the  direct 
drive.  The  brake  control  consists  of  band  brake  on  the  fly  wheel 
and  two  sets  of  rear  hub  brakes,  the  outside  hub  brakes  being 
friction  bands,  and  the  inside  brakes  of  the  expansion  type.  The 
clutch  lever  by  the  forward  movement  sets  the  brakes  similar  to 
the  high  speed  lever  on  the  Winton  Touring  Car.  A  separate 
foot  lever  controls  the  fly-wheel  brake.  The  frame  construction 
is  of  armored  wood  with  body  hangers  of  sheet  steel.  Both  front 
and  rear  springs  are  semi-elliptical.  The  steering  gear  shaft  ex- 
tends through  the  body-side  to  which  a  drop  lever  connects  to  the 
upper  end  of  the  right  wheel  steering  knuckle  through  a  horizon- 
tal link  parallel  to  the  frame.  The  cooling  system  consists  of  two 
tanks  integral  with  the  cylinder  jackets;  two  separate  circulating 
pumps,  and  a  single  radiator  placed  at  the  forward  end  of  the 
car.  The  oiling  is  by  the  standard  Winton  system  of  positive 
feed  lubrication.  The  gasoline  tank  is  placed  at  the  rear  of  the 
seat  and  has  a  capacity  for  200  miles  continuous  running.  The 
wheel  base  of  this  machine  is  9  feet  6  inches,  with  a  standard 
tread  of  56^2  inches.  The  wheels  are  equipped  with  34x41/2  tires. 
The  Winton  Bullet  No.  2  has  been  used  by  only  one  profes- 
sional racing  man,  Barney  Oldfield,  in  whose  hands  it  has  proved 
the  most  successful  racing  automobile  on  either  side  of  the  At- 
lantic. It  has  won  26  races,  6  second  and  3  third  prizes  in  36 
starts,  and  holds  all  the  world's  track  records  from  one  mile  in 
54  4-5  seconds  to  fifteen  miles  in  14:21.  It  has  never  been  driven 
in  a  track  race  or  record  trial  beyond  fifteen  miles.  With  this 
machine  Barney  Oldfield  won  the  straight-away  world's  cham- 
pionship on  the  sand  beach  at  Daytona,  Fla.,  in  January,  1904, 
defeating  Wm.  K.  Vanderbilt,  Jr.,  in  his  Mercedes  car,  which 
is  the  highest-powered  and  fastest  automobile  ever  imported  to 
this  country. 

The  Riker=Locomobile  Car. — A  prominent  American  car, 
built  on  French  lines,  is  that  known  as  the  Locomobile.  It  com- 
bines many  features  of  exceptional  excellence,  as  regards  both 


TYPICAL   GASOLINE   CARRIAGES. 


3T7 


construction  and  operation.  Two  sizes  are  manufactured — a 
nine-horse-power,  with  a  two-cylinder  motor,  and  a  sixteen- 
horse-power  with  four  cylinders,  both  being  susceptible,  accord- 
ing to  claims  of  a  twenty-five-per-cent.  output  above  rating  at 
1,500  revolutions  or  over.  The  two-cylinder  motor,  being  ar- 
ranged for  higher  speeding,  is  capable  of  a  greater  power  output. 


FIGS. 


287.— Side  Elevation  and  Plan  of  the  Hiker-Locomobile  Chassis. 


The  Chassis  and  Running  Gear. — The  frame  of  the  vehicle 
is  of  channel  steel  bars  of  rectangular  shape,  and  suitably  braced 
at  points  intended  to  carry  the  greatest  weights.  It  is,  more- 
over, tapered  at  either  end  by  shaving  off  the  upper  arm  of  the 
C-shaped  section,  so  as  to  reduce  the  height  from  4  inches  at  the 
centre  to  2T/2  inches  at  the  extremities,  Upon  this  framework 


378 


SELF-PROPELLED    VEHICLES. 


the  body,  engine  and  all  working  parts  are  mounted,  and  it  is 
supported  on  the  two  axles  by  four  semi-elliptical  springs.  The 
wheel  base  of  the  15-horse-power  car  is  84  inches.  The  wooden 
wheels,  of  artillery  pattern,  measure  each  34  inches  diameter, 
and  are  equipped  with  3^ -inch  detachable  tires.  The  rear  axle 
is  a  solid  forging,  upon  which  the  wheels  turn  freely,  being  driven 
from*  the  countershaft.  The  axle  spindles  are  tapered  to  fit  the 
wheel  boxes,  and  are  provided  with  spiral  grooves  to  conduct 
the  oil  to  the  bearing  surfaces,  which  are  plain,  all  ball  and  roller 
bearings  being  omitted  in  these  cars. 

The  motor  has  already  been  described  in  the  foregoing  chapter, 
leaving  nothing  to  be  added  here.  The  water  circulation  is 
of  the  type  generally  used  on  heavy  gasoline  cars — the  jacket 
water  being  forced  by  the  pump  through  a  radiating  coil,  6  inches 


FIG.  288.— Sketch   of  the  Riker  Underframe,   showing  the  way  in  which   the 
channel  steel  bars  are  tapered  toward  either  end  of  the  chassis. 


in  height  by  3  inches  in  width,  and  composed  of  18  parallel  tubes. 
In  case  of  derangement  of  the  pump,  however,  the  water  tank 
is  placed  at  such  a  height  above  the  coil  as  to  permit  o-f  natural 
gravity  circulation  by  the  differing  temperatures  of  the  inlet 
and  outlet.  The  capacity  of  the  tank  is  15  gallons. 

The  engine  is  set  over  the  forward  axle,  sidewise  to  the  direc- 
tion of  travel,  and  turns  the  main  shaft  running  in  the  length  of 
the  frame,  as  in  the  standard  French  cars.  The  drive  is  through 
bevel  gears  to  the  transverse  jack  shaft,  whence  the  power  is 
transmitted  by  chains  and  sprockets  to  the  rear  wheels,  turning 
loose  on  the  dead  rear  axle.  The  usual  brakes  are  included,  one 
on  the  differential  case  sleeve  on  the  transverse  jack  shaft,  oper- 
ated by  a  foot  pedal,  the  other  on  drums  on  the  rear  wheel  hubs, 
operated  by  a  lever  to  the  right  of  the  driver's  seat. 


TYPICAL   GASOLINE   CARRIAGES. 


3T9 


The  Locomobile  Transmission. — The  transmission  gear  of 
the  Locomobile  gasoline  carriages  is  of  the  gear  type,  and 
is  arranged  to  give  three  forward  speeds  and  one  reverse,  the 
high  speed  being  direct  from  the  main  shaft.  The  efficiency  of 
this  apparatus  is  further  augmented  by  the  fact  that  the  gear- 
shifting  lever  is  automatically  locked  at  every  movement  until 
the  main  clutch  is  thrown  off,  thus  effectualy  escaping  needless 
friction  and  injury  to  the  gears.  The  cone  clutch,  which  is 
normally  held  against  the  face  of  the  flywheel  by  coiled  compres- 
sion springs,  is  bolted  to  a  flanged  sleeve  carried  on  the  squared 


FIG.   289.— The  Riker  Transmission  Gear. 

end  of  a  short  shaft,  I,  terminating  in  the  spur  pinion,  A.  This 
pinion,  as  shown  in  the  figure,  is  always  in  mesh  with  the  spur 
gear,  B,  on  a  parallel  secondary  shaft,  2,  and  continues  to  turn 
the  secondary  shaft  so  long  as  the  engine  is  in  motion.  The 
spindle  on  which  A  turns  has  a  longitudinal  bore  serving 
as  a  bearing  for  the  shaft,  3,  terminating  in  the  bevel 
pinion,  C,  in  mesh  with  the  bevel  gear,  D,  on  the 
differential  drum  of  the  "jack  shaft,"  4.  The  shaft,  3,  is  square 
through  its  entire  length  between  bearings,  and  carries  the  slid- 
ing pinions,  £  and  F.  Since  its  rotation  is  independent  of  the 


380 


SELF-PROPELLED    VEHICLES. 


clutch  sleeve,  i,  it  follows  that  all  movements  except  the  high 
speed  forward,  must  be  transmitted  from  the  secondary  shaft,  2, 
through  the  pinions,  B  and  F,  and  since  these  may  be  slid  into  a 
neutral  position-,  the  shaft,  2,  may  rotate  without  driving  the  car- 
riage. The  slow  speed  forward  is  obtained  when  gears,  B  and 
G,  are  in  mesh,  the  second  faster  speed,  when  F  and  H  engage, 


FIG.   290.— Control   Levers  and  Appliances  of  the   Riker  Car. 


and  the  reverse,  when  F  engages  idler,  K,  which  is  driven  from 
the  secondary  shaft  through  pinion,  /.  For  the  high  speed  for- 
ward, B  is  slid  to  the  right  until  internal  teeth  in  its  face  engage 
the  external  teeth  en  A,  thus  locking  the  two  and  making  the 
movement  of  shaft,  3,  continuous  with  that  of  sleeve,  i,  and  driv- 
ing the  carriage  direct  from  the  flywheel  shaft, 


TYPICAL    GASOLINE    CARRIAGES.  381 

The  Locomobile  Control  Levers. — A  carriage  using  such  a 
change-speed  gear  as  that  of  thx.:  Locomobile  2  and  4-cylinder 
cars  can  be  readily  controlled  by  the  use  of  a  single  lever.  As 
shown  in  the  accompanying  diagram,  the  inner  of  the  two  levers 
sliding  in  notched  quadrants  may  be  moved  forward  through  the 
three  forward  speeds,  and  pulled  back  for  the  reverse,  the  clutch 
being,  meantime,  thrown  out.  On  account  of  the  high  power 
and  ready  control  of  the  engine,  it  is  possible  to  operate  the  car- 
riage on  the  high  gear  most  of  the  time,  thus  requiring  that  the 
lever  be  manipulated  only  when  hill-climbing  or  other  special 
necessities  demand.  The  outer  lever  represents  the  emergency 
hub  brake,  as  in  other  makes  of  carriage,  while  the  main  brake  on 
the  differential  drum  is  operated  by  a  speed  pedal  to  the  right 
of  the  steering  pillar.  Similarly,  the  clutch  may  be  thrown  by 
depressing  the  lever  to  the  left  of  the  pillar.  The  spark  and 
hand  throttle  handles  are  set  •  at  the  end  of  rods  beside  the 
steering  pillar,  within  easy  reach  of  the  right  and  left  hand,  re- 
spectively. But  an  auxiliary  throttle  pedal  or  accelerator  is  oper- 
ated by  a  pedal  beside  the  brake ;  thus  enabling  the  carriage  to 
be  perfectly  operated  without  removing  either  hand  from  the 
steering  wheel.  The  throttle  connections  having  already  been 
shown,  it  will  not  be  necessary  to  describe  them  here. 

The  Packard  Car. — The  Packard  four-cylinder  touring  car  is 
one  of  the  best  examples  of  American  machine  constructed  on 
French  lines  Its  motor  cylinders  are  cast  in  pairs  integral  with 
their  valve  chambers  and  water  jackets.  Both  inlets  and  ex- 
hausts are  mechanically  operated  from  one  cam  shaft,  being  set 
on  the  same  side  of  the  cylinders. 

The  framework  is  of  angle-steel,  slightly  tapered  toward  either 
end,  and  supported  on  the  springs  above  the  axles.  According 
to  the  usual  plan,  the  motor  is  placed  forward  under  a  Mercedes 
type  square  front  bonnet,  and  is  connected  by  a  clutch  to  the 
transmission  gear.  The  latter  apparatus,  by  an  excellent  varia- 
tion on  current  models,  is  hung  just  forward  of  the  rear  axle, 
and  drives  direct  to  the  differential  drum  by  bevel  gears.  This 
arrangement  saves  the  extra  complication  of  a  transverse  jack 
shaft,  with  chain  and  sprocket  connections  to  loose-turning  drive 
wheels.  The  live  rear  axle  is  enclosed  in  a  strongly  enforced 
sleeve  casing,  while  a  longitudinal  adjustable  strut,  or  distance- 


382  SELF-PROPELLED   VEHICLES. 

rod,  connects  it  by  fixed  distance  at  the  centre  of  the  body  frame 
to  the  left  of  and  below  the  universal  joint  of  the  driving  shaft. 

• 

The  Clutch  and  Brakes. — The  clutch  is  of  the  expanding 
band  brake  type,  and  is  arranged  to  be  thrown  out  by  pressing 
forward  on  a  pedal  to  the  left  of  the  steering  wheel.  As  in  other 
high-powered  cars,  there  are  two  sets  of  brakes,  the  first  set  by  a 
foot  pedal  to  the  right  of  the  steering  wheel,  the  second — the 
emergency  brake — by  a  hand  lever  rising  to  the  right  of  the 
driver's  seat,  according  to  the  familiar  arrangement.  A  notable 
variation  from  the  usual  design  is  found  in  the  fact  that  neither 
of  them  acts  upon  the  differential  drum,  or  on  any  part  of  the 


FIG.    291.— Packard    Voiture   .Legere   Tonneau    Touring   Car. 

drive  shaft.  The  pedal  brake  is  an  expanding  band  within  each 
of  the  rear  axle  drums,  while  the  lever  brake  is  a  constricting 
band  acting  upon  the  outer  circumference  of  each  of  these  drums. 
The  internal  brake  consists  of  a  cast  iron  ring  split  at  the  top, 
with  an  egg-shaped  cam  so  arranged  between  the  two  ends  that 
.the  whole  ring  may  be  expanded  and  made  to  bear  against  the 
inner  surface  of  the  drum.  As  may  be  understood  from  an  ex- 
amination of  the  sectional  elevation  of  the  Chassis,  the  cam  will 
expand  the  ring,  if  the  lever  be  carried  to  an  extreme  position, 
either  backward  or  forward.  This  involves  that  the  connections 
be  carefully  adjusted,  in  order  to  have  the  lever  rest  in  the  neu- 
tral position.  The  external  band  brakes  are  of  the  ordinary  pat- 


TYPICAL   GASOLINE   CARRIAGES. 


383 


384 


SELF-PROPELLED   VEHICLES. 


tern,  and  are  actuated  by  a  backward  pull  on  the  lever.  If  both 
brakes  be  set  at  the  same  time  the  resistance  is  sufficient  to  stop 
the  car  within  a  very  small  distance. 

The  Transmission. — The  transmission  gear,  hung  just  for- 
ward of  the  rear  axle,  is  of  the  sliding  gear  type,  giving  three 
forward  speeds  and  one  reverse  As  shown  in  the  accompany- 
ing sectional  diagram,  it  consists  of  three  shafts :  ( I )  the  drive 
shaft  connected  by  a  universal  joint  to  the  clutch,  and  square 
through  the  greater  part  of  its  length  to  allow  of  sliding  a  sleeve 
holding  two  spur  gears;  (2)  the  bevel  pinion  shaft,  carrying  a 


FIG.    292.— End   View   and    Cross    Section   of   the    Packard    Expanding   Band 
Clutch. 


single  spur  gear  at  its  inner  end  and  bored  to  serve  as  a  bearing 
for  the  drive  shaft;  (3)  the  second  motion  shaft,  to  which  are 
keyed  three  spur  gears,  two  of  them  of  diameters  suitable  to 
mesh  consecutively  with  the  sliding  gears  on  the  drive  shaft, 
giving  the  lowest  and  intermediate  speeds,  and  the  third  con- 
stantly in  mesh  with  the  single  gear  on  the  bevel  shaft.  The  top 
speed,  as  in  the  Decauville,  Peerless,  Riker  and  other  modern 
transmissions,  is  obtained  by  sliding  the  two-gear  sleeve  all  the 
way  back  (to  the  right  in  the  diagram),  so  that  its  teeth  mesh 
with  internal  teeth  cut  in  the  circumference  of  the  bevel  shaft 
gear,  thus  making  the  drive  direct  from  the  motor.  The  reverse 


TYPICAL  GASOLINE  CARRIAGES. 


385 


386 


SELF-PROPELLED    VEHICLES. 


is  obtained  when  the  gears  on  the  sliding  sleeve  are  in  the  neutral 
position  (indicated  by  the  dotted  outlines  in  the  cut),  by  oper- 
ating the  short  reverse  lever,  thus  causing  an  idler  pinion,  hung 
on  a  bell  crank,  to  be  thrown  into  mesh  with  the  forward  (left) 
end  gears  of  the  drive  and  top  shafts. 


NEUTRAL  POSITION/  /DIRECT  DRIVE  POSITION 

FIG.  294.— Diagram  of  Control  Levers  and  Transmission  of  the  Packard  Car. 

The  Peerless  Car. — The  Peerless  four-cylinder  car  combines 
several  excellent  features  borrowed  from  both  French  and  Amer- 
ican masters.  The  framework  is  of  cold-rolled  pressed  angle- 
steel,  fully  reinforced  by  trussing.  The  engine  has  the  four 
cylinders  cast  separately,  integral  with  their  jackets  and  valve 
chambers,  the  valves  being  mechanically  operated  from  cam 
shafts  on  either  side  of  the  cylinders.  The  friction  clutch,  set  on 
the  end  of  the  main  shaft  of  the  engine,  differs  from  the  usual 
type  in  the  fact  that  the  male  cone  is  contained  within  the  female 
cone,  the  friction  surfaces  being  normally  held  together  by  a 
powerful  spring  pressing  outward  and  backward,  instead  of  in- 
ward and  forward,  as  in  older  types. 

As  shown  in  the  accompanying  sectional  diagram,  the  fly- 
wheel, A,  is  a  driving  fit  to  R,  and  is  bolted  to  the  flange,  Z.  The 


TYPICAL   GASOLINE   CARRIAGES. 


38' 


conical  clutch  rim,  B,  being  bolted  upon  the  fly-wheel.  The  uni- 
versal coupling,  D,  connects  with  the  transmission  gear,  has  a 
bushing,  E,  and  runs  freely  on  the  motor  shaft,  S.  The  collar, 
F,  is  keyed  to  the  universal  coupling,  D,  by  key,  G,  and  the  cone, 
C,  is  riveted  to  F,  thus  making  C,  D  and  F  practically  one.  At 
M  is  a  band  of  leather  riveted  to  the  rim  of  C,  thus  completing 
the  clutch.  The  surface,  M,  is  always  held  firmly  against  the  in- 


Fic.  295.— Internal  Cone  Clutch  of  the  Peerless  Car.  A,  engine  fly-wheel;  B, 
female  cone;  C,  male  cone;  D,  universal  coupling  on  male  cone;  E,  bush- 
ing on  D;  F,  collar  keyed  on  D;  G,  key;  H,  ball  bearings  for  taking  up 
the  thrust  on  disengaging  clutch;  J,  flange  on  ball  cone;  K,  receptacle 
on  D  for  operating  yoke;  L,  spiral  spring  for  retaining  clutch  surface 
contact;  M,  leather  band  riveted  on  C,  giving  good  friction  surface;  Q, 
main  shaft;  R,  portion  of  shaft  turned  down  to  fit  fly-wheel;  S,  portion 
of  shaft  turned  down  to  receive  clutch  sleeve;  Z,  flange  to  which  fly- 
wheel is  b'olted. 

FIG.  296.— Bevel  Driving  Apparatus  on  Rear  Axle.  A  and  B,  sleeve  and  case 
for  axles  and  gears;  D,  the  driven  gear;  E,  driving  pinion;  G,  ball  bear- 
ings on  E;  H,  H,  universal  couplings  on  the  differential;  K,  K,  K,  adjust- 
ments; L,  yoke  for  flexible  driving  shaft. 


wardly  inclined  rim  of  B  by  the  strong  spiral  spring,  L.  At  the 
points  indicated  by  H  are  the  ball  bearings,  designed  to  take  up 
the  thrust,  when  disengaging  the  clutch,  by  pressure  along  the 
shaft  from  point,  K,  where  a  yoke  is  fitted  and  slid  by  a  series 
of  levers  from  pedals  before  the  driver's  foot.  At  /  is  a  flange 
on  the  ball  retainer,  H,  turning  freely  on  shaft,  D. 


SELF-PROPELLED    VEHICLES. 


-»  0) 


3  ri  oj-      ,    c 


. 


TYPICAL   GASOLINE   CARRIAGES. 


389 


The  Peerless  Transmission. — The  transmission  used  on  the 
Peerless  carriage  closely  resembles  that  of  the  Decauville,  vary- 
ing from  it  principally  in  the  manner  of  engaging  the  reverse. 
As  in  the  Decauville  transmission,  the  driving  shaft  ends  in  a 
single  spur  gear  constantly  in  mesh  with  the  large  end  gear  on 
the  parallel  second  shaft,  and  bored  longitudinally  to  serve  as  the 
bearing  for  the  slide-gear  shaft  squared  through  its  entire  length 
between  bearings  and  carrying  two  gears  on  a  sliding  sleeve.  As 
in  other  similar  transmissions,  the  top  speed  is  obtained  when 
the  sleeve  is  slid  all  the  way  forward  (to  the  right  in  the  dia- 
gram), so  that  internal  teeth,  cut  on  its  inside  circumference, 


FIG.  298.— Diagram  of  the  Peerless  Transmission.  A,  pinion  on  shaft  coupled 
to  clutch  at  L,  B,  C,  pinions  on  sleeve  sliding  on  square  section  of  shaft, 
H,  journaled  into  A,  as  shown  in  sectional  view;  D,  pinion  on  counter- 
shaft, P,  giving  low  speed  in  mesh  with  C;  E,  reverse  pinion  on  yoke 
pivoted  at  N;  F,  pinion  giving  second  speed  in  mesh  with  B;  G,  pinion 
always  in  mesh  with  A;  H,  square  section  of  drive  shaft;  J,  brake  drum; 
K  yoke  for  coupling  on  flexible  drive  shaft;  L,  flexible  joint  coupling; 
M,  M,  M,  chain  bearing  oilers;  N,  pivot  and  lever  of  yoke  carrying  E, 
that  is  moved  forward  (to  the  right)  when  a  pin  at  I  engages  fork,  thus 
bringing  C  and  D  into  mesh  with  E  for  reverse.  High  speed  forward  is 
obtained  when  internal  teeth  in  E  fit  over  external  teeth  on  A,  giving 
direct  drive  from  the  motor  from  L  to  K. 

engage  the  external  teeth  on  the  clutch-shaft  gear.  Since  this 
latter  gear  is  always  in  mesh  with  the  end  gear  of  the  second 
shaft,  the  second  and  third  speeds  are  obtained  by  meshing  be- 
tween the  second  shaft  gears  and  those  on  the  sliding  sleeve. 
The  reverse  is  obtained  when  the  sleeve  is  slid  all  the  way  back 
(to  the  left),  so  that  the  rear  gear  meshes  with  an  idler  shown 
beneath  the  second  motion  shaft.  Since  this  idler  spur  is  hung 
on  a  bell-crank  device  having  a  fork  to  engage  a  pin  on  the  slid- 
ing sleeve  between  the  gears,  it  is  slid  forward,  as  the  sleeve  is 
slid  back,  so  as  to  engage  the  rear  spur  on  the  second  motion 


390 


SELF-PROPELLED    VEHICLES. 


shaft,  thus  bringing  the  two  shafts  into  gear  and  causing  the 
motion  to  be  transmitted  in  reverse  direction.  The  drive  is  by 
bevels  direct  to  the  differential  drum  on  the  rear  axle,  the  trans- 
mission gear  being  hung  midway  on  the  frame.  As  in  standard 
makes  of  car,  there  are  two  brakes,  both  of  the  clamping  or  con- 
stricting band  type ;  the  first  on  a  drum  to  the  rear  of  the  trans- 
mission case,  operated  by  a  foot  lever ;  the  second  on  drums  on 
the  rear  axles,  operated  by  a  lever  at  the  driver's  right  hand. 

The  Haynes=Apperson  Cars. — The  name  of  Haynes-Apper- 
son  is  well  known  as  among  the  earliest  of  American  automobile 


FIG.  299.— Plan  Sketch  of  Chassis  of  the  Haynes-Apperson  Tonneau  Car.  A 
speed-shifting  lever;  B,  bell  crank  for  shifting  speeds;  C,  silent  chain 
between  the  main  shaft  and  the  speed  shaft;  D,  driving  chain  between 
sprockets  on  clutch  shaft  and  rear  axle;  E,  main  shaft  of  motor;  F, 
speed  gear  shaft;  G,  speed  clutch  shaft;  H,  swinging  rod  for  changing 
speeds,  moved  by  B;  M,  motor;  R,  cellular  radiator. 

builders.  Indeed,  with  the  exception  of  the  Duryea  brothers, 
they  rank  as  the  pioneers  of  the  industry  in  this  country.  Their 
cars  have  always  been  propelled  by  the  double-opposed  cylinder 
engine,  already  described.  In  the  earlier  models,  the  engine  was 
always  set  back  in  the  body  frame,  throwing  the  bulk  of  the 
weight  over  the  rear  axle,  and  thus  attaining,  according  to 
claims,  a  superior  balance.  In  the  recently  perfected  tonneau  car 
the  motor  is  set  forward  under  a  hood,  as  in  the  approved  French 
models,  and  produces  quite  as  good  results. 

The  frame  is  of  angle-steel,  rounded  at  the  four  corners  and 
trussed  by  cross  braces  that  also  serve  as  supports  for  the  en- 


TYPICAL    GASOLINE   CARRIAGES. 


391 


gine  and  other  parts.  All  shafts  turn  in  roller  bearings,  which 
give  superior  endurance,  and  are  arranged  to  take  all  end  thrusts 
without  the  use  of  balls. 


The  Carburetter  and  Throttle. — The  fuel  gas  is  supplied  to 
the  two  cylinders  of  the  engine  by  two  separate  carburetters,  which 
are  of  special  design  long  used  on  cars  of  this  make,  and  permit 
of  such  exact  adjustment  as  to  allow  the  speed  to  be  varied  be- 
tween 135  and  i, 600  revolutions  per  minute.  Each  carburetter 


FIG.  300.— Sectional  Diagram  of  the  Haynes-Apperson  Throttling  Mixer.  A, 
air  inlet;  B,  gasoline  inlet;  C,  C,  location  of  air  ports  into  mixing  cham- 
ber; D,  vapor  exit  to  engine;  E,  mushroom  valve  held  on  seat  by  spring, 
•  opened  by  suction  of  engine  piston;  F,  threaded  needle  valve  spindle;  G, 
spring  for  raising  upper  member  of  air  chamber  when  released  by  screw 
motion  of  the  levers  attached  to  cover  retaining  screw  and  needle  valve 
spindle,  both  being  raised  or  lowered  by  the  same  movement. 

consists  essentially  of  a  mushroom  valve,  arranged  to  open 
against  a  tension  spring  under  suction  of  the  engine  piston,  al- 
lowing gasoline  to  enter  the  combustion-  space  through  a  needle 
valve,  and  air  through  a  variable  inlet  chamber.  The  spindle  of 
the  needle  valve  is  threaded,  so  that  its  lift  may  be  regulated  by 
rotary  movement,  screwing  or  unscrewing  in  its  socket.  The  air 
inlet  chamber  may  be  varied  in  size  and  inlet  capacity  by  a  cylin- 
drical cover  held  in  place  against  the  tension  of  a  coiled  spring 
around  a  sleeve  slid  over  the  needle  valve  housing.  This  sleeve 


392 


SELF-PROPELLED    VEHICLES. 


is  also  threaded  above  the  top  of  the  air  chamber  cover,  so  that 
a  lever  worked  in  a  rotary  direction  by  the  throttling  link  may 


FIG.  301.— The  Haynes-Apperson  Transmission  Gear,  shown  hung  on  the 
crankshaft,  as  in  the  lighter  cars.  The  reverse  is  now  accomplished  by 
a  chain  between  F  and  F',  dispensing  with  the  idler,  "V. 

allow  the  cover  to  rise  or  cause  it  to  lower,  as  the  necessity  oc- 
curs for  increasing  or  reducing  the  supply  of  air  for  the  mixture. 


TYPICAL   GASOLINE   CARRIAGES.  393 

Since  the  same  lever  handle  controls  the  lift  of  the  needle  valve 
and  of  the  air  chamber  cover,  the  proportions  of  air  and  gasoline 
vapor  may  be  maintained  within  moderately  fixed  limits.  The 
opening  of  the  needle  valve  may  be  varied  from  a  few  thou- 
sandths of  an  inch  upward,  within  limits,  and  only  a  very  slight 
movement  of  the  stem  suffices  to  increase  the  gas  supply  or 
shut  it  off  entirely.  The  throttle  is  operated  by  a  foot  button 
coming  through  the  floor  before  the  driver's  seat,  and  a  little 
practice  enables  very  exact  regulation  of  the  speed.  There  are 
two  sets  of  brakes,  as  on  other  standard  carriages,  the  first  on 
the  differential  drum,  operated  by  a  foot  lever  on  the  floor;  the 
other  on  the  rear  wheel  hubs,  operated  by  a  lever  at  the  left  of 
the  driver's  seat. 

The  Haynes=Apperson  Transmission  Gear. — The  Haynes- 
Apperson  transmission  consists  of  two  parallel  shafts,  A  and  B, 
the  former  being  driven  direct  from  the  crank,  or  by  belt  and 
pulley  from  the  main  shaft,  as  in  the  later  models  of  this  carriage, 
and  carrying  four  gears,  C,  D,  H  and  F,  keyed  in  its  length.  The 
countershaft,  B,  also  carries  four  loose  gears,  C',  D',  E'  and  F', 
each  of  which  is  bolted  to  a  band  clutch  drum,  as  shown  in  the 
illustration.  Each  of  these  brake  drums,  with  its  attached  gear, 
turns  loose  on  a  separate  drum,  G,  which  is  keyed  to  the  'counter- 
shaft, all  of  the  attached  gears,  however,  being  able  to  turn 
through  the  motion  imparted  from  their  mates  on  the  main  shaft, 
without  transmitting  power  to  the  driving  mechanism.  As  may 
be  readily  understood,  in  order  to  transmit  power  through  any 
one  of  the  gears  on  the  countershaft,  it  is  necessary  to  make  it 
rigid  with  its  drum,  G.  The  driving  sprocket  is  keyed  to  the  end 
of  shaft,  B,  as  shown. 

As  will  be  seen  in  the  separate  cut,  each  one  of  the  drums,  G 
carries  two  arms,  H  and  ] ,  fixed  diametrically  opposite  one  an- 
other. On  the  arm,  H,  is  carried  a  lever  arm,  K,  pivoted  at  L, 
and  having  a  short  angle  of  movement  by  the  attachment  of  its 
pivot  to  the  bearings,  shown  at  M  and  N.  On  the  two  extremi- 
ties of  the  arms,  R  and  J,  are  carried  brackets,  which  hold  the 
leather  brake  band  against  the  circumference  of  the  drum  turning 
loose  on  G.  One  end  of  this  brake  band  is  riveted  to  the  brake 
on  H,  the  other  to  a  forged  strap,  P,  having  at  its  extremity  the 
lug,  Q,  through  which  works  the  adjusting  screw,  R,  whose  point 


394:  SELF-PROPELLED   VEHICLES. 

bears  against  the  dog,  $.  This  dog.  S,  is  carried  on  the  square 
section,  T,  of  the  shaft  attached  to  the  lever  arm,  K,  already  men- 
tioned ;  so  that  a  slight  movement  of  the  lever,  K,  to  the  left,  is 
imparted  to  the  dog,  S,  whose  point  bears  against  the  screw,  R,  on 
the  lug,  Q;  thus  drawing  the  strap,  P,  tight  around  the  drum, 
which  is  thereby  made  rigid  with  the  sleeve,  G,  keyed  to  the  shaft, 
B.  By  this  means  the  gear  attached  to  that  particular  drum  im- 
parts the  motion  transmitted  to  it  from  its  mate  on  the  shaft,  A, 
to  the  countershaft,  B,  such  motion  varying  in  speed  according 
to  the  ratios  between  the  meshed  gears.  The  act  of  giving  the  re- 
quired axial  movement  to  the  lever  arm,  K,  is  performed  as  fol- 
lows: 

The  sleeve,  W ,  sliding  on  the  countershaft,  B,  carries  four  rin- 
gers, C" ,  D" ,  E",  P",  of  differing  length,  as  shown  in  the  fig- 
ures. In  the  extremity  of  each  of  these  fingers  is  a  lug,  such  as 
is  shown  at  X  and  Y,  the  object  of  which  is  to  engage  the  point 
of  the  lever,  K,  on  some  one  of  the  four  arms,  H,  thus  causing 
it  to  move  its  dog,  5*,  and  tighten  the  brake  band,  as  already  ex- 
plained. In  order  to  accomplish  this  act  without  interference,  the 
positions  of  the  levers,  K,  and  of  the  dogs,  S,  differ  in  each  brake 
drum.  On  drum,  C,  for  example,  it  is  at  the  top  of  the  shaft ; 
in  H'  it  is  at  the  bottom ;  while  in  D'  and  F'  it  is  on  the  right 
angle  in  either  direction.  For  this  reason,  as  may  be  understood 
from  the  cut,  the  four  fingers  carried  on  the  sleeve,  IV,  are  simi- 
larly disposed,  in  order  that  their  lugs,  X  or  Y.  may  engage  the 
point  of  the  particular  lever,  K,  which  it  is  intended  to  actuate, 
without  interference.  In  order  that  the  fingers,  K,  may  slide 
through  the  drums,  G,  keyed  to  the  shaft,  B,  four  suitable  chan- 
nels penetrate  the  entire  series  of  drums,  G,  as  shown  at  Z  in  one 
of  the  cuts. 

The  sliding  sleeve,  W ,  is  shifted  by  a  lever  working  on  the 
thimble  on  its  outer  extremity,  and  by  causing  its  fingers  to  pene- 
trate the  channels,  Z,  more  or  less,  can  give  three  speeds  forward 
and  a  reverse.  The  reverse  is  accomplished  when  the  lug  on  the 
finger,  F",  engages  the  lever,  K,  on  the  sleeve,  G,  belonging  to 
drum  and  gear,  F',  which  act  enables  the  motion  of  pinion,  F,  on 
shaft,  A,  to  be  transmitted  through  the  idler,  V,  to  F',  which  will 
of  course,  rotate  in  an  opposite  direction  to  F,  thus  reversing 
the  motion  of  the  shaft,  B.  In  more,  recent  models  of  this  gear, 
F  and  F'  are  sprockets  and  are  connected  by  a  chain  belt,  which 


TYPICAL   GASOLINE   CARRIAGES.  395 

accomplishes  the  end  of  reversing  the  travel  of  the  carriage  to 
better  advantage  than  by  the  use  of  the  idler,  V.  The  lever  oper- 
ating the  speed-changing  works  through  a  bell  crank  to  spool, 
W. 

The  Pope=ToIedo  Car. — The  Pope-Toledo  car  is  driven  by 
the  four  cylinders  already  described  in  the  preceding  chapter. 
The  cylinders  are  cast  separate,  the  heads  and  valve  chambers 
being  bolted  on,  as  shown  in  the  diagram.  The  inlet  valves  are 
operated  solely  by  suction,  as  in  the  older  types  of  motor,  the 
mechanical  operation  having  been  abandoned  by  the  manufactu- 
rers, in  spite  of  the  fact  that  they  were  among  pioneer  users 
in  America.  The  clutch  is  of  the  internal-cone  type,  and  is  sus- 
ceptible of  easy  operation  and  ready  adjustment.  As  shown  in 
the  accompanying  diagram,  the  fly-wheel,  A,  is  bolted  to  a  flange 
on  the  main  shaft,  P,  and  carries  on  its  rim  the  clutch  ring,  B, 
which  forms  the  female  portion  of  the  clutch  mechanism.  The 
clutch  sleeve,  H  connects  at  one  end  to  the  transmission  through 
a  universal  joint  being  bolted  at  the  other  end  to  the  clutch  cone, 
D.  The  leather  band,  H,  is  riveted  to  the  rim  of  D,  thus  com- 
pleting the  clutch.  Four  strong  spiral  springs,  /,  hold  the  cone, 
D,  firmly  against  B.  Each  may  be  adjusted  by  the  clutch  spring 
nuts,  K.  The  fork  for  operating  the  clutch  fits  into  the  groove 
at  H.  It  is  geared  to  a  pedal  at  the  left  of  the  steering  wheel, 
but  is  so  connected  that  it  is  automatically  drawn  when  either  of 
the  brakes  is  applied. 

The  Toledo  Transmission. — The  transmission  gear  used  on 
this  car  is  of  a  somewhat  different  type  from  those  previously 
described.  As  shown  in  the  accompanying  diagram,  shaft,  A, 
driven  by  the  motor,  communicates  the  power  to  the  sliding 
gear  sleeve,  U,  through  the  two  bevel  gears,  C.  Sleeve,  U,  car- 
ries sliding  gears,  D  and  D',  and  the  male  portion,  O,  of  a  miter 
gear  clutch.  These  parts  are  free  to  move  endwise,  but  are  pre- 
vented from  turning  independently  by  long  feathers  set  in  oppo- 
site sides  of  the  sleeve.  The  sleeve,  U,  is  free  to  turn  on  the 
transverse  transmission  shaft,  B.  Directly  below  this  shaft  is  a 
countershaft,  which  carries  gears,  F,  F'  and  P. 

The  driving  gear,  H,  is  not  fixed  to  the  differential  case,  but 
may  be  held  in  driving  relation  thereto  by  the  spring,  Q,  which 


396 


SELF-PROPELLED    VEHICLES. 


normally  presses  the  spur-driving  gear,  H,  against  hub,  H,  and 
causes  teeth  on  the  right-hand  face  of  its  hub  to  mesh  with  simi- 
lar teeth  on  H,  which  is  integral  with  the  differential  gear  case. 
When  teeth  on  £  mesh  with  those  on  H,  E  is  locked  to  the  differ- 
ential case.  This  relation  exists  only  when  the  car  is  being  driven 
on  the  slow  or  intermediate  speed  or  the  reverse.  It  will  be  seen 
that  when  driving  on  the  slow  speed,  sliding  gear,  D,  meshes 


FIG.  302.— Detail  Section  of  the  Pope-Toledo  Clutch.  The  parts  are:  A,  fly- 
wheel; B,  clutch  ring;  C,  clutch  ring  screw;  D,  clutch  cone;  E,  clutch 
leather;  F,  clutch  bolt;  G,  clutch  bolt  nut;  H,  clutch  sleeve;  I,  clutch 
sleeve  bush;  J,  clutch  spring;  K,  clutch  spring  plug;  L,  clutch  spring 
plug  nut;  M,  clutch  spring  stem;  N,  clutch  spring  plate;  O,  ball  thrust 
collar;  P,  crank  shaft;  Q,  fly-wheel  stud;  R,  fly-wheel  stud  nut. 


with  gear,  F,  on  the  countershaft,  and  power  is  transmitted 
through  the  shaft  and  pinion,  P,  which  is  in  mesh  with  gear,  E. 
The  ratio  of  this  gear  system  is  8  to  I.  On  the  intermediate 
speed,  sliding  gear,  D',  meshes  with  pinion,  P',  on  the  counter- 
shaft, and  the  power  is  conveyed  to  the  driving  shaft  through 
pinion,  P,  and  gear,  H,  as  before.  The  ratio  of  this  combination 


TYPICAL   GASOLINE   CARRIAGES. 


397 


398 


SELF-PROPELLED    VEHICLES. 


is  5  to  I.  In  reversing,  sliding  gear,  D,  is  meshed  with  pinion, 
G,  and  power  is  transmitted  through  the  reverse  shaft  and  pinion, 
6*',  and  gear,  F. 

In  driving  on  the  high  speed,  the  only  gears  in  mesh  between 
the  motor  and  the  driving  wheels  are  the  bevel  gears,  C.  This  is 
accomplished  by  sliding  the  gear  set,  DDr,  to  the  left  until  its 
miter  teeth,  O,  are  in  mesh  with  those  on  hub,  H.  This  move- 
ment also  pushes  gear,  E,  to  the  left  sufficiently  to  disengage 
miter  gears  on  its  hub  from  those  on  H,  thus  releasing  the  coun- 
tershaft and  establishing  a  positive  connection  between  sleeve,  U, 
and  the  differential.  On  returning  to  the  lower  speeds,  spring, 
Q,  again  establishes  a  positive  driving  relation  between  gears  E 
and  hub  H. 


FIG.    304.— Columbia    Four-cylinder    Tonneau    Carriage. 

Further  reference  to  the  drawing  of  the  transmission  will  show 
that  ball  bearings  are  used  extensively,  the  bearings  being  unusu- 
ally long,  while  every  opportunity  for  close  adjustment  is  afford- 
ed by  the  construction. 

The  Columbia  Carriages. — Among  recent  American  cars 
modeled  on  French  lines  are  the  24  and  36  horse-power  4-cylinder 
Columbia  tonneau  vehicles.  The  engines  are  notable  for  effi- 
ciency, and  for  the  fact  that  all  valves  and  other  parts  are  readily 
detachable,  when  necessary,  without  the  use  of  tools  of  any  kind. 
•The  inlet  valves  are  secured  by  a  locking  device  similar  to  that 


TYPICAL  GASOLINE  CARRIAGES. 


399 


used  on  the  breech-blocks  of  large  rifled  guns ;  a  ^-turn  of  the 
handle  enabling  removal.  Transmission  is  by  longitudinal  shaft, 
connected  by  bevel  gears  to  transverse  countershaft.  A  cone 
clutch  connects  speed  gear  to  flywheel,  as  in  typical  French  cars. 
The  change-speed  apparatus  is  of  sliding  gear  type,  gears  being 


FIG.   305.— Elevation    of    Chassis    of    the    Columbia    Four-cylinder    Tonneau 
Carriage. 


FIG.  306.— Plan  of  Chassis  of  the  Columbia  Four-cylinder  Tofmeau  Carriage. 


cut  to  coarse  pitch  to  facilitate  engaging,  giving  four  forward 
speeds  and  one  reverse. 

A  single  lever  slides  all  gears,  including  reverse.  It  operates 
in  a  gridiron  quadrant  equipped  with  a  hinged  latch,  preventing 
engaging  the  reverse  accidentally.  An  interlocking  device  also 
obliges  throwing  out  of  the  clutch  before  changing  speeds. 


400 


SELF-PROPELLED   VEHICLES. 


In  construction  and  operation,  this  gear  closely  resembles  the 
Cannstadt-Daimler  already  described,  having  a  lever  arranged 
to  move  laterally,  as  well  as  backward  and  forward,  thus  shift- 
ing one  single  and  one  double-faced  gear  on  the  square  sepa- 
rate section  of  the  main  shaft.  Unlike  the  former  apparatus, 
however,  the  highest  forward  speed  is  obtained  by  sliding  the 
third  speed  gear  forward,  so  as  to  cause  it  to  engage,  by  a  claw 
clutch  device,  the  constantly  meshed  driving  pinion  of  the  main 
shaft,  thus  making  the  two  pairs  of  the  main  shaft  continuous 
and  driving  direct  from  the  clutch  shaft,  as  in  the  Decauville, 


FIG.   307.— Columbia  Light  Tonneau  Touring  Car. 


Darracq,  Locomobile,  Peerless  and  Packard  transmissions.  The 
reverse  is  accomplished  by  swinging  an  idler  pinion  of  broad  face 
between  the  two  low-speed  gears,  set  in  neutral  position,  as  in  the 
Daimler  transmission  already  described. 

The  drive  wheels  turn  loose  on  rear  dead  axle,  driven  by  chain 
and  sprocket  from  extremities  of  countershaft,  each  sprocket 
carrying  drum  of  main  brakes.  Auxiliary  brakes  are  attached 
to  rear  wheel  hubs.  The  countershaft  turns  in  plain  bearings. 
The  differential  gears  may  be  locked,  so  that,  in  event  of  a  broken 
chain,  the  car  may  be  driven  on  one  wheel. 


TYPICAL   GASOLINE  CARRIAGES. 


401 


A  light  vehicle  of  this  make,  driven  by  a  double  opposed 
cylinder  engine,  5x4.1/2,  set  over  the  front  axle  in  a  conventional 
bonnet,  and  developing  between-  12  and  14  horse-power,  has  an 
interesting  variety  of  control  system,  as  shown  in  the  accompany- 
ing diagram.  As  in  several  other  American  carriages,  the  trans- 
mission is  by  a  longitudinal  shaft  and  bevel  gears  to  the  differ- 
ential drum. 

The  clutch  control  foot  pedal,  to  the  left  of  the  steering  post, 
opens  the  friction  clutch  when  pressed  down  and  closes  it  when 


FIG.  308.— Plan  Showing  Lever  and  Control  System  of  the  Columbia  Two- 
cylinder  Light  Carriage.  A  is  the  dash;  B,  foot  accelerator  lever  for 
controlling  engine;  C,  foot  brake  lever;  D,  clutch  lever;  E,  clutch  in- 
terlock, requiring  that  clutch  be  thrown  before  brakes  are  set;  F,  igni- 
tion-timing lever  on  steering  wheel;  G,  clutch  interlock;  H,  second  and 
third  speed  lever;  J,  first  speed  and  reverse  lever;  K,  hub  emergency 
brake  lever;  L,  brake  rocker;  M,  expanding  brake  on  driving  shaft;  N, 
rear  live  axle;  O,  hub  brake. 

allowed  to  rise.  It  is  fixed  on  a  shaft  having  a  small  finger  in- 
terlocking the  foot  brake  lever  on  the  right  of  the  steering  post, 
so,  that,  when  the  clutch  pedal  is  pressed  down,  no  effect  is 
created  upon  the  brake  pedal.  But  owing  to  a  pin  projecting 
in  front  of  the"  small  interlock  on  the  clutch  shaft,  when  the  brake 
pedal  is  pressed  down  the  clutch  pedal  is  caused  to  go  back  and 
release  the  clutch.  The  brake  connections  run  to  the  rear  and 


402 


SELF-PROPELLED    VEHICLES. 


connect  by  a  bell  crank  lever  to  the  expanding  brake  band  on  the 
transmission  shaft.  This  brake  is  applied  beyond  all  the  universal 
joints  on  the  propeller  shaft,  so  that  they  receive  no  braking 
strains. 


FIG.  309.— Mechanism  of  the  Expanding  Band  Clutch  of  the  Columbia  Light 
Car. 


FIG.  310.— Transmission  and  Clutch  of  the  Columbia  Light  Car.  A,  spur 
gear  on  the  clutch  shaft;  B  and  C,  spurs  on  the  squared  second  shaft, 
the  first  shifted  by  fork  hung  at  H,  by  lever,  H  (last  figure),  the  second 
by  fork  at  J  by  lever,  J.  D,  E,  F,  G,  three-speed  pinions  keyed  to 
countershaft;  K,  pinion  giving  reverse  when  in  mesh  with  C  and  G;  L,, 
clutch. 


The  emergency  brake,  to  the  left,  also  connects  to  the  clutch 
pedal  by  a  slip  interlock,  so  that  when  it  is  pressed  down,  the 
clutch  pedal  is  also  pulled  off.  Its  connections  run  aft  and  con- 
nect to  band  brakes  on  the  driving  wheel  hubs. 


TYPICAL   GASOLINE,    CARRIAGES.  403 

The  gear  change  control  is  shown  on  the  left  side  directly  in 
front  of  the  emergency  brake  lever.  In  practice,  the  tatter  is 
outside  of  the  vehicle  seat,  while  the  gear  change  levers  pro- 
ject up  inside  of  the  seat.  As  in  this  vehicle  the  engine  power  is 
very  high  in  proportion  to  the  weight  of  the  vehicle,  ordinary 
service  requires  that  the  middle  and  the  high  gears  are  the  only 
ones  used.  They  are  thus  controlled  by  one  handle  which  is  made 
conspicuous.  For  such  backing  and  rilling  as  is  necessary  in 
turning  in  close  quarters,  another  handle  gives  the  reverse  and 
low  gear  ahead.  To  set  the  medium  gear,  the  conspicuous  handle 
is  pulled  back  as  far  as  it  will  go;  for  the  high  speed  it  is  to  be 
pushed  ahead  as  far  as  it  will  go  regardless  of  notches  or  other 
indexes.  A  small  snap  indicates  the  off  position.  Similarly,  to 
set  the  back  gear,  the  second  lever  is  pulled  back  as  far  as  it  will 
go,  and,  to  set  the  low  gear  ahead,  it  is  pushed  forward  to  the 
end  of  the  slot.  One  lever  cannot  be  moved  unless  the  other  is  in 
the  off  position.  This  makes  the  control  very  simple  and  avoids 
a  possibility  of  injury  to  any  one  of  the  gears,  and,  as  will  be 
noticed,  also  gives  the  great  advantage  of  being  able  to  get  to 
zero  from  any  one  gear  without  having  to  engage  any  other. 

The  motor  accelerator  is  operated  by  a  small  foot  lever  pro- 
jecting from  the  dash.  By  pressing  it  down  the  throttle  is  opened 
beyond  the  governing  position  and  maximum  power  is  obtained. 

Under  normal  conditions  this  pedal  returns  to  the  governing 
position.  Small  teeth  hold  it  in  any  accelerated  position  de- 
sired. For  very  low  engine  speeds,  such  as  are  desired  when 
the  vehicle  is  standing,  the  pedal  is  trapped  to  the  left  by  the  foot, 
so  that  it  springs  up  beyond  the  governing  position  to  a  small 
but  fixed  throttle  opening.  This  is  adjustable,  so  that  for  stand- 
ing speeds  as  low  as  100  revolutions  are  possible. 

The  Duryea  Carriage  and  Control. — The  well-known  Duryea 
carriage  is  notable  for  several  original  and  exclusive  features  of 
construction.  Unlike  the  typical  automobile  or  horse-carriage, 
it  is  built  entirely  without  an  underframe,  the  wheel  axles,  front 
and  rear,  being  connected  direct  to  either  end  of  the  heavily  built 
body.  The  principal  advantages  claimed  for  this  "reachless  con- 
struction" are  that  extra  weight  and  complication  are  saved, 
while  greater  compactness  and  accessibility  of  parts  are  rendered 
possible.  As  shown  in  an  accompanying  cut,  the  three-cylinder 


404  SELF-PROPELLED   VEHICLES. 

motor  already  described,  is  placed  beneath  the  driver's  seat  with 
the  change-speed  gear  and  other  moving  parts.  This  change- 
gear,  or  "power  drum,"  as  already  explained,  allows  two  forward 
speeds  and  a  reverse,  although  all  ordinary  driving  is  done  on  the 
high  speed,  the  parts  of  the  power  gear  being  stationary  with 
relation  to  each  other,  and  the  speed  of  the  carriage  being  con- 
trolled entirely  by  throttling. 

The    Duryea    Transmission    Gear. — The    transmission    gear 
used  on  the  Duryea  carriages,  shown  in  section  and  part  plan 


FIG.  311.— Elevation  of  the  Duryea  Three-cylinder  Car.  A,  the  motor;  D,  the 
magneto  generator;  H,  brake  pedal;  I,  gasoline  tank;  M,  tubular  panel 
for  passage  of  water  from  tank,  V,  to  water  jacket;  N,  oil  cup  on  motor; 
O,  muffler;  R,  6-cell  battery;  S,  extra  seat  in  front;  U,  cellular  water 
tank,  cooled  by  draft  deflected  by  wings  from  side  of  vehicle. 

in  the  accompanying  illustrations,  is  operated  entirely  by  friction 
clutches,  entirely  avoiding  the  wear  and  constant  danger  of  break- 
age involved  in  the  use  of  shifting  gears.  The  small  gear,  A,  is 
secured  to  the  motor  shaft  against  the  flywheel  flange  by  screw 
threads.  Meshing  with  it  are  three  planet  or  idler  gears  marked 
A',  which  are  journaled  upon  studs  provided  on  a  triangular 
frame  to  receive  them.  This  frame  is  journaled  upon -an  ex- 
tension of  the  motor  shaft,  the  planet  gears  being  held  concentric 
with  the  driving  gear,  A,  and  is  double,  one  part  being  formed 
integral  with  the  studs  and  the  other  part  attached  to  the  studs 


TYPICAL   GASOLINE   CARRIAGES. 


405 


by  nuts  on  their  projecting  ends.  This  latter  part  carries  the  re- 
verse ring,  H,  while  both  parts  of  the  frame  form  supports  for  the 
clutch  pins,  P,  and  their  actuating  levers,  M,  of  which  the  func- 
tions will  be  described  later.  Encircling  the  planet  gears,  A', 
is  an  internal  gear,  X,  attached  to  the  slow-speed  ring,  B,  which 
is  supported  upon  the  disc,  H,  by  projecting  lugs ;  while  the  disc, 
H,  in  turn,  is  journaled  so  as  to  remain  concentric  with  the  motor 
shaft,  and  thus  support  the  internal  gear,  X,  in  concentric  rela- 
tion and  proper  alignment  with  the  other  parts.  Friction  bands, 
not  shown,  are  attached  to  the  framework  of  the  vehicle  and 


"Fie.  312.— Plan  View  of  Duryea  Three-cylinder  Car.  B,  bearing  for  speed 
gear;  C,  distance-rod  from  rear  axle  for  taking  up  the  pull  of  the  chain; 
D,  the  magneto-generator;  G,  pedal  for  operating  the  reverse  clutch: 
II,  brake  pedal;  I,  gasoline  tank;  P,  central  single  control  lever;  R,  6-cell 
battery.  Front  axle  shorter  than  rear  to  prevent  skidding  and  promote 
ease  in  turning. 


encircle  the  rings,  H  and  B,  being  provided  with  levers  by  which 
either  band  may  be  caused  to  grip  its  corresponding  ring  at  the 
will  of  the  operator.  If  the  reverse  ring,  H,  is  gripped  by  its  band, 
the  planet  gear  studs,  with  the  attached  framework,  will  be  held 
stationary  and  the  motion  of  the  motor  will  be  transmitted  from 
the  gear,  A,  through  the  planet  gears,  A',  to  the  external  ring, 
driving  same  in  a  reverse  direction,  as  shown  by  the  arrows  in 
the  plan.  If  the  slow-speed  band  is  gripped  upon  its  ring,  B,  the 


406 


SELF-PROPELLED    VEHICLES. 


FIG.  313.— Sectional  Elevation  of  the 
Duryea  Change  Speed  Gear.  A  is 
a  spur  gear  screwed  to  the  main 
shaft;  A',  one  of  the  three  idler 
pinions  studded  to  disc,  B;  C,  one 
of  the  three  wedges  used  for  lock- 
ing B  and  E  with  friction  cone,  D; 
F,  sliding  sleeve  on  main  shaft; 
F',  ball  race  around  F  for  attach- 
ing the  shifting  lever;  G,  toggle 

joint  operated  by  shifting  sleeve,  F;  M,  lever  for  raising  or  lowering  pin,  P; 
X,  an  internal  gear  on  disc,  B;  Y,  a  groove  containing  perforations  for  ad- 
mitting pins,  P,  when  H  and  B  are  locked  together. 


TYPICAL    GASOLINE   CARRIAGES. 


407 


internal  gear  will  be  held  in  a  fixed  position  and  the  motion  of 
the  motor  will  cause  the  planet  gears,  A',  to  roll  around  inside 
the  internal  gear  in  the  same  direction  as  the  gear,  A,  carrying 
the  studs  of  the  planet  gears,  A' ,  with  their  framework,  slowly 
in  a  forward  direction,  as  will  be  explained  later.  If  all  parts  are 


FIG.  314.— Front  Elevation  of  the  Duryea  Change  Speed  Gear.  The  lettering 
here  refers  to  the  same  parts  as  in  the  previous  figure.  N  marks  the 
position  of  the  lever,  M,  when  pins,  P,  are  inserted  in  holes.  Y,  in  D. 
M'  marks  the  position  of  lever,  M,  when  pins,  P,  are  raised  from  holes 
in  D.  R  and  R,  arms  of  the  spider,  carrying  the  three  idler  pinions,  A', 
and  sliding  in  a  groove  on  H  to  the  pins,  T  and  T'. 


locked  together  in  any  convenient  manner  so  as  to  prevent 
relative  motion,  they  will  then  move  with  the  motor  and  cause 
the  driving  sprocket  to  move  at  high  speed  forward,  while  if  no 
clutch  is  in  engagement  the  motion  of  the  motor  will  turn  the 
gears  idly  without  producing  motion  of  the  sprocket. 


408  SELF-PROPELLED    VEHICLES. 

More  specifically,  these  various  motions  are  accomplished  as 
follows : 

The  planet-gear  frame  is  normally  held  in  engagement  with 
the  sprocket-carrying  disc,  D,  by  means  of  the  pins,  P,  so  that 
holding  the  internal  gear,  X,  by  means  of  the  slow-speed  band — 
the  other  clutches  being  released — it  carries  the  sprocket  forward 
at  slow  speed.  Since  the  planet-gear  frame  and  the  disc,  D,  are 
normally  in  engagement,  it  is  evident  that  clutching  the  ring,  X, 
to  the  disc,  D,  will  prevent  relative  motion  of  the  planet  gears 
and  the  internal  gear,  and  thus  cause  the  sprocket  to  be  carried  at 
the  speed  of  the  motor.  This  effect  is  produced  by  means  of 
conical  friction  surfaces  on  D,  engaged  by  complementary  sur- 
faces inside  the  ring,  B,  and  the  disc,  E,  which  surfaces  are 
brought  in  contact  by  means  of  the  wedge,  C,  bearing  against  the 
disc,  H,  under  the  roller  attached  to  the  lug  projecting  from  the 
ring,  B.  This  wedge,  C,  is  operated  by  a  shifting  collar,  F,  and 
toggle  link,  G;  a  shifting  lever,  not  shown,  being  attached  to 
the  outer  ring  of  the  ball  bearing,  F'.  The  section  shows  these 
surfaces  in  engagement ;  releasing  being  effected  by  moving  the 
shifting  collar,  F,  toward  the  sprocket,  which  withdraws  the 
wedge,  C,  and  permits  the  friction  surfaces  to  be  separated  by 
the  spring  shown.  The  large  surfaces  and  the  toggle  and  wedge 
arrangement  for  closing  them,  secure  a  very  powerful  pressure 
with  little  shifting  effort,  while  the  disc,  D,  is  ordinarily  surfaced 
with  brass,  which,  having  a  higher  expansion  co-efficient  than  the 
cast  iron  against  which  it  bears,  is  rapidly  heated,  in  case  of  slip- 
ping, and  becomes  self-tightening  by  expansion.  Releasing  all 
the  clutches  allows  the  sprocket  with  its  disc,  D,  and  the  planet- 
gear  frame  to  stand  idle  while  the  internal  gear  revolves  freely  in 
a  reverse  direction,  as  shown  by  the  arrows,  although  the  motor 
may  be  running. 

The  reversing  effect  is  secured  by  holding  the  ring,  H,  which 
is  mounted  on  the  arms  of  the  planet-gear  frame,  in  such  a  man- 
ner that  the  frame  may  move  a  short  distance  before  it  is  stopped 
by  pins,  T',  which  motion  moves  the  lever,  M,  into  the  dotted 
position  M',  and  withdraws  the  pin,  P,  from  engagement  with 
the  disc,  D,  thus  separating  the  planet-gear  frame  from  the 
sprocket  disc,  D.  Since  the  pins,  7V,  prevent  further  movement 
of  the  planet-gear  frame,  while  the  disc,  D,  is  free  to  move  in  any 
direction,  it  is  evident  that  the  motion  of  the  motor  will  drive 


TYPICAL    GASOLINE    CARRIAGES. 


409 


the  internal  gear,  X,  in  the  reverse  direction,  and  that  clutch- 
ing the  gear,  X,  to  the  sprocket  disc,  D,  by  means  of  the  high- 
speed clutch,  will  cause  the  sprocket  to  be  carried  in  the  reverse 
direction  along  with  the  gear,  X.  It  is  further  evident  that  re- 


FIG.  315.— Central  Control  Lever  for  Steering,  Throttling  and  Operating  the 
Clutches.  When  arm,  J,  is  raised  by  an  upward  movement  of  handle, 
N,  the  low  clutch,  is  set;  when  depressed,  the  high  clutch  is  set;  in 
neutral  position,  both  are  thrown  out.  The  reverse  is  operated  by  a  foot 
pedal. 

leasing  the  high-speed  clutch  will  stop  the  reverse  movement 
of  the  sprocket,  while  releasing  the  reverse  ring,  H,  will  permit 
the  pins,  P,  to  resume  their  normal  position,  under  the  action  of 
iheir  springs, 


410  SELF-PROPELLED    VEHICLES. 

The  whole  device  is  placed  by  the  side  of  the  motor,  on  a  short 
extension  of  the  motor  shaft,  and  the  power  is  transmitted  from 
the  driving  gear,  A,  to  the  various  clutch  surfaces,  in  approx- 
imately a  single  plane,  which  lessens  the  torsion  strains  and  gives 
great  strength  with  little  weight.  All  parts  are  concentric  or 
balanced,  and,  therefore,  adapted  for  use  at  high  speeds. 

The  most  interesting  feature  of  this  carriage  is  the  single  cen- 
tral controlling  lever,  by  which  the  three  different  functions  of 
driving  the  vehicle — steering,  throttling  and  setting  the  clutches — 
are  easily  and  readily  performed  by  one  hand.  It  consists  of  a 
casting,  A,  pivoted  on  the  forward  edge  of  the  seat  to  swing  side- 
wise.  It  has  oppositely  projecting  arms  below  the  seat  to  which 
the  tensile  steering  connections,  B  B,  are  attached,  while  up- 
ward and  slightly  forward  the  tube  or  lever  proper,  C,  projects. 
Bushings,  D  D,  at  each  end  support  a  smaller  tube,  B,  within  the 
main  tube,  which  smaller  tube  slides  up  or  down  and  carries  at 
its  lower  end  a  long  pinion,  F.  This  pinion  engages  (substan- 
tially in  the  axis  of  the  pivot)  a  rack,  G ,  having  diamond  shaped 
teeth  which  permit  the  lever  to  be  swung  to  the  extremity  of  its 
motion  in  either  direction  without  damaging  the  teeth  of  the 
rack  and  permitting  the  rack  to  be  operated  by  rotating  the 
pinion,  F,  in  any  position.  This  rack  is  attached  near  the  right- 
hand  side  of  the  wagon,  while  the  other  end  of  the  lever  operates 
the  throttle  slide.  The  pinion  is  bored  out,  and  in  it  is  swiveled 
a  stud,  H,  carrying  rollers,  /  /,  which  engage  the  shifting  lever, 
/,  so  that  sliding  the  internal  tube,  £,  up  or  down  carries  the 
shifting  lever,  Jf  up  or  down  with  it,  and  permits  setting  the 
clutches,  while  in  no  way  interfering  with  either  the  steering  or 
the  throttling.  The  end  of  the  shifting  lever  is  bent  to  the  arc 
described  by  the  rollers  ^in  their  normal  working  position,  and 
any  slight  variations  are  readily  provided  for  by  the  hand  of 
the  operator.  The  upper  bushing,  D,  on  the  steering  lever  is 
provided  with  an  internal  groove,  K,  while  the  internal  tube  has 
in  it  a  lever,  L,  with  a  projecting  end  adapted  to  engage  this 
groove  and  lock  the  tube,  £,  in  the  middle  position  with  the 
clutches  off.  By  pressing  the  safety  button,  M,  in  the  handle, 
N,  this  catch  may  be  disengaged  to  permit  setting  either  the 
high  or  low  speed  clutches. 

This  controlling  device  being  centrally  placed  permits  the 
operator  to  sit  on  either  side  of  the  vehicle.  The  design  of  the 


TYPICAL   GASOLINE   CARRIAGES. 


411 


steering  mechanism  is  such  that  it  is  irreversible  and  will  run 
over  an  obstruction  "hands  off"  without  perceptible  deflection 
from  the  course.  This  fact  relieves  the  controlling  lever  from 
all  unpleasant  vibration,  and  no  muscular  effort  is  needed  to  hold 
the  vehicle  in  its  course.  A  slight  pressure  on  either  side  of  the 
lever  will  deflect  the  vehicle.  It  is  therefore  possible  to  steer 
with  the  thumb  and  finger,  and  throttle  by  twisting  the  handle. 
The  central  position  of-  the  lever  puts  it  out  of  the  way  in  mount- 
ing or  dismounting  and  makes  it  much  handier  than  any  other 
possible  position  of  the  controlling  device. 


FIG.     316.— Oldsmobile     Six-horse-power     Runabout. 

The  Oldsmobile  and  Control. — The  popular  Oldsmobile  is  a 
typical  form  of  the  reachless  side-spring  construction,  also 
adopted  by  the  Knox  and  other  light  and  medium  weight  Ameri- 
can gasoline  carriages.  The  underframe  consists  of  two  6-leaf 
longitudinal  side-springs,  each  5  feet  6  inches  long,  arranged 
parallel  at  a  distance  of  30  inches ;  rigidly  secured  to  axles  at 
cither  end.  The  motor  and  moving  parts  rest  on  three-sided 
angle  steel  frame  or  central  horizontal  portions  of  the  springs 
below  and  within  body  of  carriage.  This  arrangement  gives 


412 


SELF-PROPELLED    VEHICLES. 


/     Cylinder 

2.  Crank  Case. 

3.  BalanccWtiee-l. 

rjre  Clutch. 


Speed  Ct 
8.  ClutcA-SAa/t. 
9.CSutcA.  Lever. 
(fas-ait  ne  Tank. 
Oiler    Hanctte 
Starte 
/S.  ttdtnoua 


Mixer. 
17.  Suctton  Screen 


ater  Reservoir. 
2Z.  Muffler. 
23. 
24. 


2.5.  Sn  d 

2.6.  •Steercn^ 

e  fiod. 
26. 

23.  Seeder  ttot  Lever. 
3O. 
3/.    l)riisiny  Chain. 

32.  Worm  Gear. 

33.  JYee  die 

34.  f?e  lief  Lever. 

35.  ^fartiny  Crank. 

inff  Chain. 

37.  Cam  Shaft. 

38.  Crank  -Shaft 

39.  Lef  (Double  Bracket. 


41.,  Coucr  to  Cra.  nh  Case. 
4Z.  Water  Coot  cr. 
Rever 


47.  Cylinder  Oiler. 


FIG.  317.— Plan  View  of  Oldsmobile  Body  and  Controlling  Apparatus, 


TYPICAL  GASOLINE  CARRIAGES. 


413 


great  distortability,  enabling  the  carriage  to  take  uneven  roads 
without  jar  or  inconvenience,  better  than  with  many  patterns  of 
swivel- jointed  tubular  frames. 

The  horizontal  one-cylinder  engine  is  set  midway  on  the  central 
support  of  the  side-springs,  with  the  change-speed  gears  on  the 
main  shaft.  The  water-circulation  system  is  controlled  by  a 
rotary  pump  operated  from  the  shaft  through  a  flexible  joint, 
which  preserves  it  from  shocks  due  to  motor  pounding.  The 
radiating  tubes  are  arranged  in  two  horizontal  layers  across  the 


FIG.   318.— Plan  of  Chassis  of  Oldsmobile. 

carriage,  water  being  drawn  from  the  lower  to  the  upper  row  by 
the  pump ;  the  cooling  being  effected  without  the  use  of  fins  or 
ribs,  as  in,  most  other  forms  of  tubular  radiator.  The  starting 
crank,  fixed  permanently  on  outside  of  carriage  body,  turns  shaft 
parallel  to  and  at  the  rear  of  clutch  shaft.  Transmits  rotary 
movement  to  main  shaft  through  chain  and  sprocket.  When  the 
engine  turns  over  under  its  own  power,  the  starting  shaft  is 
automatically  thrown  out,  a,nd  ceases  rotation. 


414 


SELF-PROPELLED    VEHICLES. 


Transmission  is  directed  by  chain  and  sprocket  connections 
from  the  main  shaft,  through  the  two-speed  planetary  gear.  This 
apparatus  consists  of  two  band-clutch  drums,  internally  geared ; 
actuating  planetary  pinions;  one  giving  low  speed,  the  other  the 
reverse  movement.  The  high  speed  is  obtained  by  throwing  in 
a  sliding  bevel  friction  clutch  at  the  end  of  the  shaft,  thus  driving 
the  sprocket  direct  from  the  engine  shaft.  The  gear  is  operated 
from  a  simple  clutch  shaft,  having  a  three-throw  cam  arrange- 
ment, throwing  either  forward  speed  or  reverse  by  movement  of 


FIG.  319.— Sectional  Elevation  of  the  Oldsmobile  Runabout.  A,  the  speed 
shifting  and  reversing  lever;  B,  the  battery  switch;  C,  the  spark-con- 
trolling lever;  D,  the  starting  crank;  E,  starting  handle;  F,  oiler  handle; 
G,  needle  valve;  H,  relief  lever;  K,  brake  foot  lever;  L,  speeder  foot 
lever;  M,  water  reservoir;  N,  gasoline  tank;  P,  brake  drum  on  rear 
wheel  hub. 


one  handle,  through  rotation  from  reverse,  to  low  speed,  to  high 
speed;  but  from  high  speed  direct  to  reverse,,  low  speed  not  en- 
gaging ;  brake  bands  lock  and  unlock  automatically  in  this  order. 
The  main  brake  drum  set  on  the  shaft  with  speed  gear  drums, 
is  operated  by  a  pedal  on  the  floor  of  the  carriage.  There  is  an 
auxiliary  brake  on  the  differential  drum,  for  checking  rotation 
of  the  road  wheels  in  case  of  chain-breakage.  The  transmission 
chain  is  tested  by  a  straight  pull  of  4,000  pounds. 


TYPICAL   GASOLINE   CARRIAGES. 


415 


The  Oldsmobile  Transmission.  —  The  two-speed  and  reverse 
transmission  of  the  Oldsmobile  is  of  the  planetary  gear  type.  The 
reverse  and  low  speed  forward  are  operated  by  band  and  drum 
clutches,  and  the  high  speed  forward  by  a  friction  compression. 
clutch.  A  single  shaft  carrying  three  eccentrics,  with  the  throws 
different  directions,  serves  to  actuate  all  three  —  the  two 


n 


former,  by  tightening  bands  around  the  brake  drums,  the  latter, 


^Oi/  fa/ff. 


FIG.   320.— Section   of  Oldsmobile   Two-Speed   and   Reverse   Transmission. 


through  a  bell  crank  moving  in  a  direction  longitudinal  to  the 
main  shaft.  As  shown  in  the  sectional  diagram,  two  spur  gears 
are  keyed  to  the  main  shaft.  Each  of  these  gears  meshes  with 
planetary  pinions  studded  to  a  frame  or  spider  arranged  to  turn 
with  a  sleeve  loose  on  the  shaft.  Furthermore,  the  pinions  mesh 
with  internal  gears,  so  that  the  entire  system  may  rotate  at  once, 


SELF-PROPELLED    VEHICLES. 

or  the  planet  pinions  may  turn  on  their  axes  over  the  internal 
gears.  Close  examination  of  the  section  will  show  that  the  in- 
ternal gear  of  the  reverse,  the  sprocket,  the  main  brake  drum  and 
the  pinion  frame  of  the  forward  gear  are  rigidly  held  together 
by  a  pin,  so  as  to  rotate  as  a  unit.  When  neither  of  the  bands 
is  applied  the  rotation  of  the  two  spurs  on  the  main  shaft  is 
transmitted  through  the  planetary  pinions  to  the  brake  drums, 
leaving  the  driving  apparatus  stationary.  The  reason  for  this  is 
obvious  for,  since  the  internal  gear  of  the  reverse  and  the  pinion 
frame  of  the  forward  speed  are  rigidly  connected  on  one  sleeve, 
they  obviously  cannot  rotate  in  opposite  directions.  When,  how- 
ever, the  band  is  applied  to  the  forward  speed  clutch  drum,  which 
is  the  internal  gear,  the  spur  causes  the  pinions  to  rotate  on  their 
axes  and  travel  around  within  the  internal  gear,  imparting  rota- 
tive movement  in  the  opposite  direction  to  their  frame  and  the 
sleeve  holding  the  sprocket  and  the  internal  gear  of  the  reverse. 
The  clutch  drum  of  the  reverse  gear  is  the  pinion  frame,  and 
this  being  held  rigid  by  the  band,  the  driving  spur  rotates  the 
pinions  on  their  axes,  causing  them  to  drive  the  internal  gear 
and  the  sprocket  in  the  same  direction  as  its  own  rotation,  thus 
reversing  the  movement  of  the  carriage.  The  high  speed  forward 
is  obtained  by  throwing  in  the  cone  friction  clutch  shown  at  the 
right  of  the  diagram,  the  effect  being  to  press  upon  the  high 
speed  compression  plate,  thus  holding  the  pinion  frame  and  in- 
ternal gear  in  rigid  relation,  and  causing  the  entire  transmission 
system  to  rotate  as  a  compact  whole  at  the  speed  of  the  main 
shaft. 

The  shaft  carrying  the  cams  for  locking  and  unlocking  the 
clutch  bands  and  the  high-speed  cone,  is  handled  by  means  of  a 
single  lever,  the  rotation  being  from  reverse  through  slow  speed 
to  high  speed,  but  on  returning  the  slow  speed  does  not  engage 
and  thus  the  lever  may  be  thrown  direct  from  high  speed  to 
reverse,  so  that  this  gear  may  be  used  to  aid  the  brake  in  case  of 
emergency. 

The  Stevens=Duryea  Carriage. — The  Stevens-Duryea  car- 
riage is  a  peculiarly  American  product  in  all  its  lines  of  design, 
no  trace  of  French  influence  being  discernible.  Indeed,  like  the 
three-cylinder  engine  Durvea  cars,  it  represents  the  finished 
product — in  a  somewhat  different  direction —  of  the  nearly  twenty 


TYPICAL   GASOLINE,   CARRIAGES.  417 

years  of  experiment  conducted  by  those  pioneers  of  American 
automobilism,  the  Brothers  Duryea.  The  motor,  change-gear 
and  other  apparatus  are  included  in  the  body  of  the  carriage,  and 
every  means  for  attaining  the  ends  of  compactness  and  simplicity 
of  operation  seem  to  have  been  adopted.  A  common  steering 


FIG.  321.— Motor  and  Control  Apparatus  of  the  Stevens-Duryea  Car.  Start- 
ing by  horizontal  crank;  steering-  by  upright  crank;  speed  shifting  by 
hand  lever  at  left;  throttling  by  button  at  end  of  upright  lever. 

and  motor  starting  pillar  is  fixed  at  the  centre  of  the  seat;  both 
functions  being  controlled  by  hand  cranks.  The  speed-changing 
and  throttling  lever  is  set  at  the  left  hand  of  the  driver.  By  mov- 
ing this  lever  forward  or  backward  a  rack  is  moved,  which, 
through  a  spur-gear  rotates  a  camshaft  and  sets  clutches  con- 


±18  SELF-PROPELLED    VEHICLES. 

trolling  three  forward  speeds  and  one  reverse.  In  addition  to 
the  cam  shaft,  operated  by  this  rack  and  pinion  movement,  are 
two  others,  known  respectively  as  the  top  and  speed  shafts. 

"The  top  gear  shaft  is  substantially  an  extension  of  the  motor 
crankshaft  and  carries  the  clutch  hubs  keyed  to  it,  all  three  speed- 
change  gears  being  loose  on  the  top  shaft.  The  reverse  gear 
sprocket  on  the  top  shaft  is  also  loose,  and  its  chain  drives  a  loose 
sprocket  on  the  lower  or  speed  shaft,  which  can  be  engaged  by 
a  splined  solid- jaw  clutch,  actuated  by  a  treadle  from  the  driver's 
footboard.  The  top  or  gear  shaft  is  provided  with  two  double- 
acting  friction-clutch  shells,  fixed  respectively  to  the  three  cast 
iron  gears  and  the  backing  sprocket,  and  the  two  cam-actuated 
clutch  levers  can  clutch  any  one  of  the  four  loose  elements  to  the 
gear  shaft.  The  speed  shaft  has  keyed  to  it,  in  addition  to  its 
backing  sprocket  clutch,  three  rawhide  gears  of  different  diam- 
eters, meshing  with  the  cast  iron  gears  on  the  top  shaft ;  by  this 
arrangement  the  speed  shaft  is  driven  at  will  at  different  rates, 
giving  the  wagon  three  speeds  forward  and  one  backing  speed. 
Owing  to  the  peculiar  construction  of  the  cams  carried  by  the 
cam  shaft,  no  two  friction  clutches  can  be  thrown  into  engage- 
ment at  the  same  time,  hence  no  mistake  can  be  made  in  handling 
the  speed-change  lever." 

The  Cadillac  Carriage. — The  Cadillac  gasoline  carriage  is  an 
American  product,  combining  a  number  of  original  features.  Its 
first  introduction  was  in  1903,  and  since  that  time  it  has  been 
built  on  substantially  the  same  lines.  The  single-cylinder  motor 
has  already  been  described  in  the  preceding  chapter,  and  no 
tendency  has  since  been  shown  to  use  a  double  cylinder.  It 
seems  to  have  made  good  the  claims  of  its  manufacturers  in  com- 
bining good  balance  and  efficiency  in  operation. 

As  shown  in  accompanying  figures,  the  machinery  and  control 
apparatus  are  very  compactly  arranged,  and  a  good  idea  of  the 
convenience  of  operation  may  be  obtained.  The  body  frame  is 
of  angle-steel,  hot  riveted  and  trussed  at  four  points  by  trans- 
verse bars.  The  motor  and  transmission  gears  are  hung  at  the 
centre  of  the  frame,  and  the  driver's  seat  is  placed  directly  above. 
As  shown  in  the  cuts  of  plan  and  elevation  of  the  Chassis,  the 
arrangement  of  the  control  apparatus  agrees  with  that  of  the 
standard  carriages  already  described.  Here  the  steering  wheel 


TYPICAL    GASOLINE   CARRIAGES. 


419 


(20)  carries  a  quadrant  (24),  around  which  works  the  throttle 
lever.  This  lever  is  fixed  at  the  end  of  a  rod  set  parallel  to  the 
steering  pillar,  and  actuates  an  arm  (22)  below  the  floor,  con- 
nected by  a  link  (23)  to  the  throttle  arm,  and  moves  the  cam 
(25)  as  already  explained  in  connection  with  the  figure  of  the 
engine.  By  this  means  the  volume  of  the  charge  may  be  con- 
stantly regulated.  The  spark  lever,  (15)  set  at  the  right  of  the 
driver's  seat,  furnishes  another  means  of  regulating  the  engine, 
advancing  or  retarding  the  spark.  The  top  speed  and  reverse  are 
operated  by  means  of  the  hand  lever  (16),  while  the  slow  speed 
is  attained  by  the  pressure  on  the  pedal  (34)  at  the  left  of  the 


FIG.   322.— Cadillac  Car,   with   Rear   Entrance  Tonneau. 


steering  pillar.  The  pedal  at  the  right  acts  upon  the  main  brake 
on  the  differential  drum.  When  it  is  pressed  upward  and  for- 
ward, it  rotates  the  short  transverse  shaft  to  which  it  is  attached, 
causing  an  arm  to  rise  and  exercise  a  pull  upon  a  double  cable, 
thus  constricting  the  two  brake  bands  on  the  differential  drum. 
The  reverse  gear  may  also  be  used  as  an  extra  brake,  as  will  be 
presently  explained. 

The  Transmission. — The  transmission  used  on  this  car  is  of 
the  planetary  type,  its  theory  and  operation  being  readily  under- 


420  SELF-PROPELLED   VEHICLES. 

stood  from  the  accompanying  figure.  As  here  shown,  it  consists 
of  the  two  drums,  H  and  K,  the  former  of  which  is  the  reverse 
drum,  and  contains  six  studs,  L,  holding  six  spur  pinions.  Three 
of  these  pinions,  E,  are  twice  the  width  of  the  other  three,  F,  and 
all  mesh  with  pinion,  G,  which  is  of  the  width  of  the  F  pinions, 
and  is  on  a  sleeve  keyed  to  the  hub  of  the  drum,  K.  The  main 
driving  pinion,  D,  is  keyed  to  an  extension  of  the  crank  shaft, 
and  meshes  with  the  £  pinions  only,  on  tne  widened  portion 
which  projects  beyond  the  pinions,  F,  as  shown  in  the  cut.  The 
left  end  of  the  gear  case,  C,  is  fastened  to  H  by  screws.  The 
drum,  B,  on  which  is  the  internal  gear,  is  continued  through 


FIG.  323.— Sectional  Elevation  of  the  Cadillac  Chassis,  showing  operative  and 
control  apparatus,  as  explained  in  text. 


the  casing,  and  the  sprocket,  A,  forms  part  of  it.  When  the  brake 
drum,  H,  with  the  pinion  studs  upon  it,  is  held  stationary  by  a 
band  brake ;  and  when  pinion,  D,  turns  with  the  shaft  in  the  di- 
rection of  the  arrow  upon  it,  it  drives  pinion,  B,  in  the  direction 
shown  by  its  arrow,  and,  since  H's  stud  is  stationary,  H  in  turn 
drives  internal  gear,  B,  in  the  opposite  direction.  This  produces 
the  reverse.  To  obtain  the  slow  speed,  the  brake  drum,  K,  is 
held  by  a  brake  band,  and  pinion,  D,  drives  pinions,  H,  as  here- 
tofore. H  in  turn  drives  F,  but  as  G  is  stationary,  since  it  forms 
part  of  the  drum,  K,  the  pinions,  F,  travel  round  it  with  a  plane- 


TYPICAL   GASOLINE   CARRIAGES.  421 

tary  motion,  thus  turning  the  drum,  H,  slowly  and  causing 
the  pinions,  E,  to  turn  the  internal  gear  and  drum,  B,  even  more 
slowly,  but  in  the  same  direction  as  that  in  which  D  is  turning. 
For  the  high  speed,  a  leather-faced  disc,  keyed  to  the  shaft,  is 
pushed  against  the  smooth  surface  on  the  right-hand  end  of 
drum,  K,  thus  locking  K  to  the  shaft,  and  causing  the  whole 
drum  to  turn  as  one  unit  without  any  of  the  gears  revolving. 
When  the  car  is  standing  still  and  the  engine  is  running,  all  the 
gears  are  turning,  and  the  drum  is  revolving  idly  about  the  shaft. 
It  is  easy  to  understand  the  method  of  varying  the  speed  and 


FIG.  324.— Plan  View  of  Chassis  of  the  Cadillac  Car,  showing  operative  and 
control  apparatus. 


power  ratios  by  the  use  of  this  transmission.  The  control  lever 
(16)  is  attached  to  the  control  shaft  (26),  which  has  two  arms 
(27  and  28),  on  different  radii.  Arm  27  has  attached  to  its  end 
a  rod  (29)  which  engages  and  controls  the  high  speed  clutch 
(30)  in  the  manner  already  explained.  At  the  end  of  the  other 
arm  (28)  is  a  rod  (31),  which  engages  and  controls  the  reverse 
brake  band  (32).  If  the  controlling  lever  be  moved  forward, 
the  first  arm  (27)  and  its  rod  (29)  cause  the  high-speed  clutch 
to  lock  the  transmission  gearing  together  into  one  rotating  unit; 


422  SELF-PROPELLED    VEHICLES. 

so  that  it  revolves  with  the  engine  shaft  and  acts  as  an  additional 
fly-wheel,  carrying  the  driving  sprocket  (33)  around  with  it. 
If,  on  the  other  hand,  the  control  lever  ( 16)  be  moved  backward, 
the  high-speed  clutch  releases,  leaving  the  engine  free  to  run 
without  driving  the  carriage.  This  is  the  neutral  position.  If 
the  lever  (16)  be  moved  still  further  back,  the  rod  (31)  attached 
to  arm  (28)  will  be  drawn  forward  and  will  close  the  reverse 
brake  band  upon  the  reverse  drum,  H,  as  previously  explained. 
Consequently,  the  sprocket  turns  in  the  reverse  direction  at  low 
speed.  Since  the  grip  of  the  reverse  band  may  be  varied,  -so  as 
to  permit  of  more  or  less  slip,  it  is  possible  to  use  the  reverse 
as  a  brake  for  ordinary  needs. 


FIG.  325.— Diagram  of  the  Cadillac  Transmision,  giving  two  forward  speeds 
and  one  reverse. 

In  throwing  in  the  low  speed,  the  control  lever  is  set  in  the 
neutral  position,  in  which  both  the  high  speed  and  reverse  clutches 
are  released,  and  the  slow  speed  pedal  (34)  is  pushed  forward 
and  upward  by  the  flat  of  the  foot.  When  this  is  done  the  at- 
tached rod  (35)  is  moved,  and  the  slow-speed  brake  band  (36) 
is  moved  upon  the  drum,  K,  thus  causing  the  sprocket  to  revolve 
with  the  engine  shaft,  but  at  a  greatly  reduced  rate. 

The  De  Dion  &  Bouton  Speed  Gear. — The  two-speed  trans- 
mission of  the  De  Dion  &  Bouton  carriages  consists  of  a  hollow 
driving  shaft.  A,  on  which  are  two  loose  gears  and  their  clutch 
drums,  C  and  D,  and  a  secondary  shaft,  to  which  are  keyed  two 
spur  pinions,  G  and  H.  Within  the  hollow  driving  shaft,  A, 


TYPICAL   GASOLINE   CARRIAGES. 


423 


slides  a  round  shaft,  S,  upon  the  extremity  of  which  is  carried 
a  right  and  left-handed  screw,  U.  This  rod,  S,  is  arranged  to 
slide  in  the  hollow  shaft,  A,  so  that  the  right  and  left-handed 
screw,  U,  may  operate  as  a  rack  to  impart  axial  movement  to 


the  pinions,  O,  P,  O  and  7?,  which  are  'mounted  on  right  and  left 
threaded  axles,  screwing  into  adjustable  bearings  or  sleeves. 
Consequently,  as  may  be  understood,  the  longitudinal  movement 
of  the  screw  rack,  turning  the  pinions  on  their  screw  axles,  tends 


424 


SELF-PROPELLED    I  'RHICLES. 


to  force  them  in  or  out  of  the  sleeves  in  which  they  work.  The 
result  is  that  the  segments,  K  and  L,  also  shown  in  the  transverse 
section,  are  forced  firmly  against  the  internal  circumference  of 
the  drum,  D,  clutching  it  and  producing  a  rigid  driving  con- 
nection between  the  hollow  rotating-shaft,  A,  causing  it  to  carry 
around  the  entire  system,  including  the  internal  rod,  S,  double 
screw,  U,  and  the  pinions,  O,  P ,  Q  and  R.  This  rotative  move- 
ment is  insured  by  the  slides,  M,  N ,  with  which  the  segments, 
K  and  L,  are  always  in  fixed  relations. 

The  reversing  gear  used  with  this  transmission  is  equally  sim- 
ple and  effective  in  operation.  As  shown  in  the  figure,  A  is  the 
countershaft  passing  through  the  change  speed  gear;  B,  a  spur 


H 


FIG.  325c.  FIG    325d. 

FIGS.   325c,   325d.— De   Dion   &   Bouton   Reversing   Gear. 

pinion  for  driving  direct  to  the  differential  gear,  and  having  a 
bevel  gear  at  one  end  engaging  the  bevel  pinions,  C  and  D;  E,  a 
bevel  gear  keyed  to  A  at  F ;  G,  a  nut  holding  E,  in  place.  H  is  a 
sleeve  on  A,  on  which  gear,  B,  turns  loosely.  /  and  /  and  springs 
attached  to  the  brake  drum,  K,  and  holding  the  bevel  pinions.  C 
and  D ,  against  the  stop  pieces,  M  and  M.  The  reverse  motion  is 
obtained  when  the  band,  L,  is  tightened,  preventing  the  rotation 
of  K  and  drawing  bevel  pinions,  C  and  D,  from  engagement  with 
stop  pieces,  M  and  M ,  thus  allowing  them  to  rotate  on  their  own 
axes  and  reversing  the  motion  imparted  by  drive  pinion  B  to  its 
bevel  gear  end.  The  bevel  pinions,  C  and  D,  are  studded  to  a 
two-armed  spider  which,  as  shown,  turns  on  shaft  A, 


CHAPTER    TWENTY-FOUR. 

GENERAL     PRINCIPLES     OF     ELECTRICITY,     AS      APPLIED     TO 
ELECTRIC    VEHICLE    CONSTRUCTION. 

The  Use  of  Electric  Motors  on  Vehicles.— Vehicles  pro- 
pelled by  electric  motors,  whose  energy  is  derived  from  second- 
ary batteries,  are  much  preferred  by  many  authorities  on  account 
of  the  combined  advantages  in  point  of  cleanliness,  safety  and 
ease  of  manipulation.  When  well  constructed  and  well  cared  for, 
they  are  also  less  liable  to  get  out  of  order  from  ordinary  causes. 
Among  their  disadvantages,  however,  may  be  mentioned  the 
facts  that  the  storage  batteries  must  be  periodically  recharged 
from  some  primary  electrical  source,  which  fact  greatly  reduces 
their  sphere  of  efficient  operation.  Since  at  the  present  time  road 
vehicles  driven  by  electricity  are  not  the  prevailing  type,  power 
charging  stations  are  few  and  far  between  on  the  ordinary  lines 
of  travel,  and  it  is  not  possible  to  make  a  tour  of  more  than 
twenty-five  miles,  at  the  most,  from  the  base  of  supplies.  It  is 
impossible  to  counteract  this  deficiency  by  carrying  an  extra  set 
of  batteries,  since  these  are  so  immensely  heavy,  as  usually  con- 
structed, as  to  greatly  curtail  the  speed  and  carrying  power  of  the 
vehicle.  It  is  also  impracticable  to  propel  a  vehicle  by  a  battery 
of  primary  cells  carried  within  it,  since  a  battery  of  sufficient 
power  to  propel  the  vehicle  would  have  little,  if  any,  advantage 
in  point  of  endurance  over  secondary  cells,  and  when  once  ex- 
hausted must  be  entirely  replaced.  One  or  two  attempts  to  use  a 
primary  battery  on  a  motor  vehicle  have  been  recorded,  but  the 
great  waste  and  expense  involved  must  continue  to  render  such  a 
construction  more  of  a  toy  and  an  experiment  than  a  practical- 
possibility.  Some  machines,  particularly  of  European  manufac- 
ture, have  attempted  to  combine  the  use  of  electricity  with  the 
explosive  motor,  the  latter  serving  the  double  duty  of  driving 
the  carriage  and  charging  the  batteries,  which  may  then  be  used 
to  supply  energy  for  the  electric  motors.  It  must  be  said,  how- 
ever, that  such  a  carriage  as  this  is  heavy  and  complicated  to  a 
point  vastly  in  excess  of  the  advantages  supposedly  gained. 

425 


426  SHIP-PROPELLED   VEHICLES. 

Conditions  of  Electrical  Activity. — There  are  two  kinds  of 
electricity,  according  to  the  usual  classification :  static  electricity 
and  current  electricity.  As  -a  matter  of  fact,  however,  the  differ- 
ence is  rather  a  question  of  phenomena  than  of  anything  more 
fundamental.  The  term,  static  electricity,  refers  to  the  phe- 
nomena observed  in  the  charging  of  a  condenser,  and  is  attribu- 
table to  the  fact  that  a  body  of  high  electrical  potential  imparts 
a  portion  of  its  energy  to  another  having  a  lower  potential,  just 
as  a  heated  body  gives  off  a  part  of  its  heat  to  a  cold  body,  equal- 
izing the  temperature.  The  phenomena  observed  in  connection 
with  the  electric  current  differ  from  the  "shock"  of  the  static 
electricity  only  in  the  fact  that  the  current  marks  a  continuous 
passage  of  electrical  energy  from  a  point  of  high  potential  to  one 
of  lower  potential,  showing  that  the  source  of  E.  M.  F.  is  con- 
stant, just  as  a  substance  in  combustion  constantly  gives  off  heat. 
This  fact  is  shown  in  all  types  of  electrical  generators,  the  gal- 
vanic cell  operating  on  the  principle  that  the  positive,  or  high 
potential,  pole  constantly  transmits  its  energy  along  the  circuit 
to  the  negative,  or  low  potential,  pole. 

Units  of  Electrical  Measurement. — It  may  be  said  in  a  gen- 
eral way  that  the  electric  motor  has  one  point  of  advantage  over 
any  heat  engine,  in  the  fact  that  it  is  much  more  flexible  in  opera- 
tion, which  is  to  say  more  easily  regulated,  as  to  speed  and  power 
efficiency.  It  is  also  possible  to  obtain  a  vastly  closer  approxi- 
mation to  theoretical  requirements  under  the  conditions  of  prac- 
tical operation,  and  to  estimate  much  more  precisely  the  power 
efficiency  to  be  obtained  from  a  given  electrical  source  on  any 
given  circuit.  This  is  because  the  available  working  energy,  in 
terms  of  amperes,  is  in  exact  proportion  to  the  voltage  and  re- 
sistance of  the  circuit,  as  well  as  to  the  amount  of  efficient  activity 
in  terms  of  work  accomplished  and  time  consumed.  As  we  have 
already  seen,  the  power  efficiency  of  a  steam  engine  is  estimated, 
in  the  first  place,  in  terms  of  heat  and  power  units;  secondly,  in 
terms  of  foot-pounds  or  the  efficiency  of  the  engine  to  move  so 
many  pounds  through  such  a  space  in  such  a  length  of  time ; 
and  thirdly,  in  terms  of  gauge  pressure  or  estimated  temperature. 
In  short,  the  units  of  power  are  all  stated  in  terms  of  pounds, 
feet  and  seconds  in  estimating  the  power  passed  on  any  given 
electrical  circuit  The  units  of  electrical  measurement  are  stated 


ELECTRICAL   PRINCIPLES.  427 

in  terms  of  length,  weight  and  time,  which  is  to  say  in  terms  of 
centimeters,  grams  and  seconds.  This  gives  the  C.  G.  S.  units, 
as  they  are  called,  which  are  estimated  in  accordance  with  the 
decimal  system  of  measures.  The  units  thus  established  are,  of 
course,  largely  arbitrary — just  as  are  all  units — but  they  have 
been  carefully  estimated,  so  that  the  proportions  between  cur- 
rent strength,  circuit  resistance  and  voltage  may  be  accurately 
maintained. 

The  Ohm,  the  Unit  of  Resistance. — The  first  unit  of  electri- 
cal measurement  with  which  we  have  to  deal  is  the  ohm,  which  is 
the  unit  of  resistance.  This  unit  measures  not  only  the  relative 
resistance  of  a  circuit  composed  of  a  conducting  wire  of  a  given 
length  and  diameter,  as  compared  with  wires  of  different  length 
and  diameter,  composed  of  the  same  material,  but  also  the  speci- 
fic resistance,  or  resistivity,  which  refers  to  the  immense  varia- 
tions in  resisting  quality  found  between  given  wires  of  the  same 
length  and  cross-section,  made  of  different  materials.  The  dif- 
ferent resistivity  of  several  different  metals,  as  found  in  circuits, 
precisely  similar  in  all  points  of  dimensions,  is  demonstrated  in 
the  fact  that,  while  a  unit  wire  of  silver  shows  a  conductivity  of 
loo,  and  one  of  copper,  99,  a  wire  of  iron  gives  only  16.80 

The  value  of  the  ohm,  as  fixed  by  the  Electrical  Congress,  at 
the  Columbian  Exposition  in  1893,  is  equivalent  to  the  resistance 
offered  to  one  volt  of  E.  M.  F.  by  a  column  of  mercury  106.3 
centimeters  in  height  (about  41.3  inches),  and  one  square  mille- 
meter  (.00155  square  inch)  cross-section,  determined  at  the  tem- 
perature of  melting  ice  (39°  Fahrenheit).  Mercury  was  chosen 
for  this  test,  because  on  the  scale  giving  a  conductivity  of  100  to 
silver,  it  stands  1.6,  while  its  resistivity  is  99.7,  as  compared  with 
1.52  for  silver;  being  thus  very  nearly  unity  in  the  first  particu- 
lar, and  100  in  the  second.  One  ohm  is  also  equivalent  to  the 
resistance  to  be  encountered  in  one  foot  of  No.  40  B.  &  S.  copper 
wire,  which  has  a  diameter  of  .003145  inch,  or  3.145  mils;  or  to 
the  resistance  encountered  in  about  two  miles  of  the  copper  wire 
used  in  electric  trolley  lines.  In  both  cases  we  have  approximate- 
ly the  equivalent  of  the  afore-mentioned  column  of  mercury,  if 
the  test  is  made  at  a  temperature  of  45°  Fahrenheit.  In  general, 
the  resistance  of  a  circuit  varies  inversely  as  the  diameter  of  the 
wire,  and  directly  as  the  length  of  the  wire. 


428 


SELF-PROPELLED    VEHICLES. 


The  Ampere,  the  Unit  of  Current. — The  unit  of  electrical 
current  is  called  the  ampere,  which  has  been  authoritatively  fixed 
as  the  equivalent  of  the  current  strength,  which  can  deposit 
.00033  grams  of  metallic  copper,  by  the  electro-plating  process, 
in  each  second  of  time.  In  this  respect  it  measures  not  only  the 
current  intensity,  or  available  working  energy,  but  also  the  rapid- 


FIG.  326.— Diagram  of  a  Series  Circuit,  showing-  Three  Galvanic  Cells  in  Bat- 
tery. As  shown,  the  copper,  or  positive,  pole  of  the  first  cell  is  connected 
to  the  zinc,  or  negative  pole  of  the  second,  and  so  on;  leaving  a  negative 
terminal  at  one  end  and  a  positive  at  the  other.  Thus  the  current 
emerging  from  each  cell  passes  through  all  those  succeeding  in  line,  tho 
total  voltage  of  the  battery  being  equivalent  to  the  sum  of  the  individual 
voltages  of  the  several  cells.  If,  on  the  other  hand,  several  motors,  or 
other  electrically  affected  apparatus,  be  connected  in  series,  the  result 
is  to  increase  the  "back  pressure"  (C.  E.  M.  F.)  on  the  same  ratio,  and 
hence  cut  down  the  operative  efficiency  of  each. 


FIG.  327.— Diagram  of  a  Multiple,  or  Parallel,  Circuit,  showing  Three  Gal- 
vanic Cells  in  Battery.  In  this  system  of  forming  the  battery  there 
are  two  main  xead  wires,  one  connected  to  the  positive  poles  of  all  the 
cells,  the  other  to  the  negative  poles.  Unlike  the  series  system  shown 
above,  the  effect  is  that  the  total  voltage  of  the  battery  is  equivalent 
to  the  voltage  of  one  of  the  cells  only,  the  pressure  seemingly  being  cut 
down  by  this  wiring.  If,  on  the  other  hand,  a  number  of  motors,  or 
other  electrically  affected  apparatus,  be  connected  in  multiple,  the  "back 
pressure"  (C.  E.  M.  F.)  is  similarly  decreased,  enabling  each  one  to  give 
its  highest  operative  efficiency. 

ity  of  its  exercise.  The  work  above  stated  might  readily  be  ac- 
complished by  a  given  current  in  ten  seconds,  instead  of  in  one, 
but  such  a  current  would  not  have  the  value  of  one  ampere,  only 
of  i-io  ampere — since  it  required  ten  times  as  long  to  accom- 
plish the  result. 


ELECTRICAL   PRINCIPLES.  429 

Another  frequently  mentioned  analogy  for  the  ampere  is  the 
so-called  miner's  inch,  which  represents  the  product  of  an  ori- 
fice one  inch  square,  through  which  water  is  allowed  to  escape 
from  a  given  tank  or  flume,  by  the  height  of  the  column  of  water 
in  the  tank,  in  inches.  The  miner's  inch,  is,  therefore,  in  the  first 
place,  a  measure  of  rate  or  velocity,  giving  inch-seconds,  in  fact, 
or  the  number  of  cubic  inches  of  water  passed  in  each  second  of 
time.  Thus,  while  water  flows  at  the  rate  of  so  many  miner's 
inches,  the  electrical  current  flows  at  the  rate  of  so  many  am- 
peres ;  the  rate  per  second,  in  both  cases,  being  directly  rela- 
tive to  the  original  pressure  of  energy  at  the  source.  Thus,  it  is 
inaccurate  to  speak  of  an  ampere  per  second,  since  such  an  ex- 
pression means  simply  a  current  of  one  ampere;  thus  also,  in 
speaking  of  a  current  of  ten  amperes,  for  example,  we  do  not 
refer  to  the  amount  of  current  passed  in  ten  seconds,  but  to  that 
passing  in  one  second.  There  is,  however,  a  unit  of  electrical 
measurement,  which  is  called  the  coulomb,  or  ampere-second, 
which  is  the  measure  of  electrical  quantity,  being  equivalent  to 
tiie  product  of  the  amperage  of  the  current  by  the  number  of 
seconds  it  has  been  flowing. 

The  Volt,  the  Unit  of  Pressure. — Having  determined  the 
value  of  the  resistance  unit  and  current  unit,  it  is  a  simple  matter 
to  determine  the  voltage  produced  by  an  electrical  source.  One 
volt  E.  M.  F.  can  produce  a  current  of  one  ampere  on  a  circuit 
having  a  resistance  of  one  ohm.  There  are  several  specified 
equivalents  for  estimating  the  exact  value  of.  one  volt  E.  M.  F., 
but  these  usually  refer  to  the  determined  capacity  of  some  given 
type  of  galvanic  cell.  It  is  sufficient  to  say,  however,  for  ordi- 
nary purposes,  the  majority  of  commercial  chemical  cells  are 
constructed  to  yield  approximately  one  volt.  The  ordinary  Dan- 
iell  cell  used  in  telegraphy  has  a  capacity  of  1.08  volt,  and  the 
common  type  of  Leclanche  cell  gives  about  1.50. 

Ohm's  Law  of  Electrical  Circuit. — The  value  of  the  volt,  as 
just  given,  which  is  to  say,  the  amount  of  E.  M.  F.  able  to  pro- 
duce a  current  of  one  ampere  through  the  resistance  of  one  ohm, 
gives  us  a  very  good  general  statement  of  the  fundamental  prin- 
ciple of  electrical  science,  which  is  popularly  known  as  Ohm's 
Law.  This  is  a  law  of  proportions  between  the  three  factors  in 


430  SELF-PROPELLED   VEHICLES. 

the  production  of  electrical  energy,  by  which  any  one  of  them, 
as  well  as  the  total  power  efficiency  of  the  circuit,  may  be  readily 
determined. 

Ohm's  Law  may  be  specifically  stated  under  'six  heads,  as  fol- 
lows : 

(1)  The  current  is  in   direct  proportion  to  the  electromotive 
force,  and  in  inverse  proportion  to  the  resistance. 

(2)  The  current  is  equal  to  the  electromotive  force,  divided  by 
the  resistance. 

(3)  The  resistance  varies  directly  with  the  electromotive  force, 
and  inversely  with  the  current;  hence, 

(4)  The  resistance  is  equal  to  the  electromotive  force,  divided 
by  the  current. 

(5)  The  electromotive  force  varies  directly  with  the  current 
and  with  the  resistance;  hence, 

(6)  The  electromotive  force  is  equal  to  the  current  multiplied 
by  the  resistance. 

As  may  be  readily  understood,  however,  all  these  various  rules 
are  merely  so  many  different  ways  of  stating  the  proposition  in- 
volved in  the  first,  which  is,  in  fact,  simply  equivalent  to  that 
involved  in  the  definition  of  the  ohm  already  given. 

The  Watt,  the  Unit  of  Activity. — Having  stated  the  law  of 
proportions  between  the  various  component  elements  of  a  live 
circuit,  we  may  readily  see  that  the  unit  of  active  work  performed 
by  the  current  must  stand  in  some  determinable  proportion  to 
the  other  elements.  Accordingly,  we  find  that  the  unit  of  electri- 
cal activity,  which  is  known  as  the  watt,  and  which  represents 
the  rate  of  energy  of  one  ampere  of  current  under  a  pressure  of 
one  volt,  is  equivalent  to  the  product  of  the  voltage  by  the  am- 
pereage. 

Other  equivalents  of  the  watt  make  it  equal  to  the  product  of 
the  resistance  by  the  square  of  the  current,  or  the  quotient  of  the 
square  of  the  voltage  by  the  resistance.  Thus,  a  current  of  ten 
amperes  at  a  pressure  of  2,000  volts  will  develop  20,000  watts, 
as  will  also  another  given  current  of  400  amperes  at  fifty  volts. 

The  operative  capacity  of  an  electrical  motor  is  usually  stated 
in  terms  of  watts,  or  kilowatts  (1,000  watts),  which  may  be  re- 
duced to  horse-power  equivalents  by  dividing  by  746,  which  fig- 
ure indicates  the  number  of  watts  to  an  electrical  horse  power. 


CHAPTER  TWENTY-FIVE. 


ELECTRICAL    GAUGES VOLTMETERS    AND    AMMETERS. 

Electricity  Meters. — The  electrical  gauges,  ammeters  and 
voltmeters,  used  on  automobiles  are  constructed  on  the  principle 
of  the  D'Arsonval  galvanometer,  with  either  a  permanent  or  a 
variable  field.  With  several  of  the  more  prominent  manufac- 
turers the  former  construction  seems  to  be  the  one  most  approved. 
The  general  features  are  a  small  oscillating  solenoid  whose  core 
is  mounted  on  jeweled  bearings,  arranged  like  a  dynamo  arma- 
ture between  the  poles  of  the  permanent  horseshoe  magnet,  with 
a  hand  or  pointer  pivoted  at  the  bearing,  so  as  to  indicate  the 
variation  in  electrical  conditions  on  a  graduated  scale.  A  coiled 
steel  spring  attached  at  the  base  of  the  needle  acts  to  restrain  and 
control  its  movements,  thus  ensuring  reliable  indications  of  cur- 
rent strength  or  intensity. 

Construction  of  the  Volt=Ammeter. — The  permanent  mag- 
nets used  on  such  instruments  are  of  a  special  quality  of  hardened 
steel,  magnetized  to  a  point  somewhat  below  the  full  magnetic 
capacity  of  the  metal,  and  possessed  of  great  permanence.  The 
pole  pieces  of  soft  steel  are  firmly  secured  to  the  feet  of  the  mag- 
net, the  joint  being  ground  and  intended  to  be  permanent.  The 
core  of  the  coil  is  arranged  to  render  uniform  the  field  in  which 
its  coil  oscillates,  and  over  it  are  wound  two  layers  of  insulated 
wire — the  first  short-circuited  on  itself,  for  the  purpose  of 
"damping  the  movement  of  the  coil  by  the  generation  of  eddy 
currents  within  it,  thus  rendering  the  instrument  a  periodic,  or 
dead-beat,  in  its  indicatons."  Above  this  short-circuited  layer, 
and  at  right  angles  to  its  direction  is  wound  the  "active  coil,"  con- 
sisting of  a  number  of  turns  of  fine  copper  wire,  to  which  current 
is  conveyed  through  the  medium  of  the  controlling  springs  at 
either  end  of  the  core  spindle.  The  principal  difference  between 
the  voltmeter  and  the  ammeter  is  that  in  the  former  the  active 
coil  is  in  series  with  a  resistance,  and  in  the  latter  is  connected 
across  the  terminals  of  a  shunt  block.  The  metal  used  in  these 

431 


432 


SELF-PROPELLED   VEHICLES. 


resistance  and  shunts  is  an  alloy  having  a  temperature  co-efficient 
of  about  .001  at  100°  Centigrade.  The  voltmeter  is,  thus,  really 
an  ammeter ;  the  resistance  serving  to  keep  the  amperage  in  step 
with  the  voltage. 

The  Indicator  Hand. — The  pointer  hand  in  such  instruments 
is  a  rod  of  hardened  aluminum  wire,  formed  up  with  an  eye  for 
attachment  to  the  axis  of  the  core,  and  a  counterpoise,  shown  in 


FIG.  328. 


FIG.  329. 


FIGS.  328  and  329.— Sectional  Diagrams  Illustrating  the  Construction  of  Volt 
and  Ammeters.  The  iron  core  is  secured  to  the  base  plate  by  a  screw. 
The  active  coil  is  shown  wound  around  it  from  end  to  end. 

the  diagrams,  at  the  opposite  end  of  the  wire.  The  whole  in- 
strument is  rigidly  mounted  on  a  cast  brass  bracket,  which 
serves  the  double  purpose  of  ensuring  perfect  rigidity  and  free- 
dom from  warping,  etc.,  and  enables  the  removal  of  the  moving 
parts  without  disturbing  the  pole  pieces. 

Forms  of  Volt-Ammeter. — For  automobile  use  a  voltmeter 
and  an  ammeter  are  usually  mounted  on  one  base,  with  their 


ELECTRICAL  METERS. 


433 


graduated  scale  cards  sufficiently  near  together  to  enable  rapid 
reading  of  battery  conditions.  After  slight  practice  the  driver 
of  an  electric  carriage  can  easily  keep  himself  informed  on  the 
amount  of  current  actually  being  used  and  on  the  probable  du- 
ration of  the  charge.  He  can  also  learn  to  know  the  point  of  full 
charge,  when  his  battery  is  connected  to  the  generator.  These 
instruments  frequently  have  the  scale  traced  on  opalescent  glass, 
so  as  to  be  illuminated  at  night  by  an  incandescent  lamp  placed 
behind  it.  As  shown  by  the  accompanying  cuts,  the  volt-am- 
meters made  by  different  manufacturers  vary  in  appearance — 
one  type  having  the  two  scales  arranged  side  by  side,  another, 
end  to  end.  The  voltmeter  indicates  the  pressure  between  bat- 


40    50    60     70    80 


FIG.  330.— Index  Scales  of  a  Voltmeter  and  an  Ammeter  for  Measuring  the 
Pressure  and  Intensity  on  a  Direct-current   Electrical   Circuit. 

tery  terminals,  both  in  charging  and  discharging,  while,  in  the 
ammeter  scale,  the  space  to  the  left  indicates  the  amperage  of  the 
charging  current,  and  that  to  the  right,  the  amperage  of  the 
charging  current  are  both  in  proportion  to  the  discharge  capacity 
of  the  battery,  it  is  a  simple  matter  to  adjust  the  charging  by  the 
volt-ammeter  readings,  to  suit  the  directions  regarding  the  par- 
ticular make  of  battery  in  use.  As  a  general  rule,  storage  bat- 
teries are  constructed  to  give  their  highest  discharge  rate  at  the 
eight-hour  discharge.  Consequently,  its  capacity  is  rated  at  40 
ampere-hours,  and  the  normal  charging  current  is  given  as  one- 
eighth  of  its  ampere-hour  rating,  or  as  the  equivalent  of  its 


434:  SELF-PROPELLED   VEHICLES. 

largest  rate  of  discharge  per  hour.  In  this  case,  accordingly, 
the  normal  charging  rate  would  be  5  amperes,  and  the  current 
may  be  adjusted  by  the  rheostat  until  the  indicator  hand  points 
to  5  on  the  left-hand  portion  of  the  ammeter  scale.  If,  however, 
the  charging  is  to  be  done  in  shorter  time  than  normal  the  am- 
perage may  be  periodically  adjusted  to  suit  directions.  The  bat- 
tery having  a  normal  charged  capacity  of  two  volts  per  cell,  is 
seldom  charged  above  2.6  volts,  on  the  average,  and  never  dis- 
charged below  1.75  volts  per  cell.  Consequently,  since  the  bat- 
tery is  always  charged  in  series,  the  use  of  pressure  is  constantly 
indicated  by  the  voltmeter  needle,  which  registers  the  total  volt- 
age of  the  battery  at  all  times  in  the  charge.  In  discharging,  it 


FIG.  331.— Weston  Volt-ammeter  of  the  Type  used  on  Electric  Vehicles. 
Other  makes  of  these  instruments  have  the  index  scales  side  by  side, 
instead  of  end  to  end. 


indicates  the  voltage  of  the  couple  in  circuit,  whether  the  battery 
unit  be  connected  in  multiple,  series-multiple,  or  series ;  showing 
for  a  4-unit  4O-cell  battery,  20,  40  and  80  volts,  respectively. 

Reading  Speed  and  Power  Output. — In  running  the  vehicle 
the  voltmeter  scale  reading  indicates  the  amount  of  charge  still 
remaining  in  the  battery — the  difference  between  1.75  and  2.6 — 
and  the  ammeter  rate  at  which  it  is  being  used.  If  the  speed 
of  a  vehicle  on  a  hard  level  road  be  determined  and  the  reading 
noted  in  connection  with  it,  the  ammeter  may  be  used  as  a  very 
good  speed  indicator  for  operation  under  similar  conditions. 


ELECTRICAL   METERS.  435 

The  ammeter  also  indicates  an  overload,  which,  if  above  a 
definite  specified  figure,  would  likely  damage  the  battery,  as  when 
attempting  to  start  with  brakes  set,  or  in,  beginning  the  ascent 
of  a  heavy  grade  from  a  standstill.  The  amount  of  power  being 
consumed  by  the  motor  is,  of  course,  always  the  product  of  the 
volts  by  the  amperes.  Thus,  with  readings  of  80  volts  and  16 
amperes,  1,280,  or  about  1.7  horse-power,  are  being  constantly 
used. 

Voltmeter  Indications. — Although  the  voltmeter  should  al- 
ways register  between  1.75  and  2.6  per  cell,  the  former  figure  in- 
dicating the  point  of  discharge — it  may  happen  that  an  unusually 
hard  road  will  bring  the  needle  temporarily  below  that  point.  Such 
indication  does  not  of  necessity  mean  that  the  battery  is  ex- 
hausted, as  on  coming  upon  a  better  road,  it  will  quickly  resume 
its  normal  reading. 


FIG.  332.— Diagram  Illustrating  the  Directions  of  the  Current  in  the  Field 
Windings  and  the  Induced  Current,  as  found  in  magnets,  solenoids  and 
dynamo  operation. 


CHAPTER    TWENTY-SIX. 

THE  CONSTRUCTION  OF  THE  DYNAMO   ELECTRICAL  GEN- 
ERATOR AND  THE  ELECTRICAL  MOTOR. 

Electrical  Induction. — Electrical  induction,  as  manifested  in 
its  simplest  form,  has  been  repeatedly  demonstrated  by  two  con- 
tiguous circuits  of  wire,  the  one  containing  an  electric  battery  or 
other  source  of  current,  together  with  a  switch  for  alternately 
opening  and  closing  the  circuit  as  desired;  the  other  circuit  of 
wire  containing  no  battery  or  other  source  of  current,  but  hav- 
ing its  terminals  connected  to  a  galvanometer.  If,  now,  we  close 
the  first  circuit,  allowing  the  current  to  flow  from  the  electrical 
source,  we  will  observe,  as  indicated  by  the  galvanometer,  that  a 
current  of  somewhat  less  strength  is  flowing  in  the  other  circuit, 
in  an  opposite  direction.  This  induced  current,  however,  is  only 
momentary,  continuing  only  long  enough  to  allow  its  strength 
and  direction  to  be  recorded.  On  opening  the  circuit,  including 
the  battery,  thus  cutting  off  the  current,  we  again  notice,  as  re- 
corded by  the  galvanometer,  that  a  current,  weaker  than  the  first 
one  observed,  is  flowing  in  the  second  circuit  in  the  same  direc- 
tion as  that  which  has  just  been  cut  off  in  the  first.  This  current 
is  also  momentary. 

In  regard  to  this  phenomenon,  several  principles  may  be 
stated : 

(1)  Increasing  the  strength  of  the  current  in  circuit  I  increases 
the  strength  of  the  momentary  current  in  circuit  2. 

(2)  Decreasing  or  cutting  off  the  current  in  circuit  I  decreases 
the  strength  of  the  current  in  circuit  2,  also  causing  it  to  flow  in 
the  same  direction  as  the  current  in  circuit  i. 

(3)  If  we  move  the  current-carrying  wire  of  circuit  i  nearer 
to  the  wire  of  circuit  2,  we  will  find  that  a  strong  current  is  in- 
duced in  circuit  2,  which  moves  in  a  direction  opposite  to  that  in 
circuit  i.    If  we  move  the  wire  in  circuit  i  further  from  the  wire 
in  circuit  2,  we  find  that  a  weaker  current  is  induced  in  circuit  2, 
moving  in  the  same  direction  as  that  in  circuit  i. 

(4)  If  the  wire  used  in  circuit  i  is  of  low  resistance  and  that 
used  in  circuit  2  is  of  high  resistance,  the  current  induced  in  cir- 

430 


DYNAMO  AND   MOTOR  CONSTRUCTION.  437 

cuit  2  will  show  a  greater  electromotive  force  than  that  flowing 
in  circuit  i.  Conversely,  if  the  wire  used  in  circuit  i  be  of  higher 
resistance  than  that  used  in  circuit  2,  the  current  induced  in  cir- 
cuit 2  will  show  a  lower  electromotive  force  than  that  flowing 
in  circuit  i. 

The  Production  of  Magnets. — The  most  familiar  operation  of 
current  induction  is  seen  in  the  production  of  an  electro-magnet, 
which  consists  of  a  core  of  soft  iron  wound  about  with  a  certain 
length  of  insulated  wire,  preferably  copper,  on  account  of  its  high 
conductivity.  As  soon  as  a  current  is  sent  through  the  wire 


FIG.  333.— Diagram  Illustrating  the  Action  of  Voltaic  Induction  Between  Two  Circuits: 
the  one  including  a  source  of  electrical  energy  and  a  switch;  the  other  including  a 
galvanometer,  but  having  no  cell  or  other  electrical  source.  The  direction  of  the 
battery  current  in  circuit  1  is  indicated  by  the  arrow;  the  arrow  in  circuit  2  showing 
the  direction  of  the  induced  current. 

coiled  about  the  iron  core,  its  effects  are  seen  in  the  fact  that  the 
core  becomes  magnetic,  attracting  iron  and  steel  bodies,  and  in 
general  exerting  an  observable  effect  upon  any  polarized  con- 
ductor, such  as  a  solenoid.  As  soon  as  the  current  in  the  insu- 
lated winding  is  cut  off,  the  iron  core  loses  its  magnetic  prop- 
erties. If,  however,  a  core  of  hardened  steel  be  similarly  wound 
with  insulated  wire,  and  a  strong  current  be  sent  through  it,  the 
result  will  be  that  the  steel  will  become  a  permanent  magnet, 


433  SELF-PROPELLED    VEHICLES. 

which  is  able  to  exert  the  characteristic  magnetic  effects  for  a 
practically  indefinite  period. 

A  bar  of  iron  or  steel  thus  temporarily  or  permanently  mag- 
netized invariably  shows  the  phenomenon  of  polarity,  manifested 
in  the  first  place  by  the  ability  to  attract  the  unlike  poles  and  re- 
pel the  like  poles  of  another  magnet,  the  poles  being  always  de- 
termined as  positive  or  negative  by  the  points  of  the  inlet  or  exit 
of  the  current,  as  in  the  case  of  solenoids.  The  magnet  can  also 
induce  a  momentary  current  in  a  closed  circuit  of  wire  in  exactly 
the  same  fashion  just  described  in  connection  with  the  ordinary 
action  of  current  induction.  These  simple  experiments  demon- 
strate the  fact  that  between  the  poles  of  any  magnet  there  is  a 
continual  operation  of  force,  the  lines  and  activity  of  which  may 
be  shown  by  scattering  iron  filings  on  and  between  the  two  ex- 
tremities. These  iron  filings,  if  allowed  to  adjust  themselves,  in 
obedience  to  the  magnetic  force  exerted  upon  them,  will  be  found 
to  be  thickest  at  the  points  nearest  the  extremities  of  the  poles, 
and  lightest  at  the  points  furthest  from  the  extremities,  in  the 
latter  positions  describing  arcs  of  circles,  thus  showing  the 
strength  and  direction  of  the  force  acting  upon  them.  Further, 
the  intensity  of  the  magnetic  force  is  shown  to  be  greatest  when 
the  two  poles  are  connected  by  a  piece  of  iron  or  steel,  known  as 
an  armature,  this  being  efficient  in  prolonging  the  magnetic  ac- 
tivity "of  a  permanent  magnet,  and  preventing  the  dissipation  of 
the  magnetic  force  through  a  much  longer  period. 

Electrical  Dynamos  and  flotors. — The  machines  for  con- 
verting mechanical  movement  into  electrical  current,  and  for 
converting  electrical  current  into  mechanical  movement,  in  other 
words,  the  dynamo  generator  and  the  electric  motor,  respectively, 
are  the  same  so  far  as  the  general  features  of  their  construction 
are  concerned.  In  operation,  however,  the  motor  is  the  exact 
reverse  of  the  dynamo.  As  just  stated,  the  theory  of  electrical 
generation  by  mechanical  means  is  that  the  lines  of  force  of  a 
magnet  should  be  cut  through,  so  that  their  strength  and  direc- 
tion at  any  point  or  at  any  time  should  be  made  to  vary  con- 
stantly. In  addition  to  this,  it  is  necessary  that  there  should  be 
some  means  of  collecting  the  current,  resulting  from  the  con- 
tinual disturbance  of  the  magnetic  field,  and  supplying  it  to  a 
circuit. 


DYNAMO  AND   MOTOR   CONSTRUCTION.  439 

The  Operative  Principles  of  a  Dynamo. — In  order  to  review 
the  principles  involved  in  both  the  generation  and  mechanical 
utilization  of  the  electrical  current,  it  will  be  necessary  briefly  to 
enter  into  somewhat  rudimentary  principles.  In  an  accompany- 
ing cut  may  be  seen  a  diagram  representing  the  simplest  con- 
ceivable dynamo  electric  generator.  As  may  be  seen,  the  spindle, 
A,  rotates  between  the  two  poles,  N  and  S,  of  the  magnet.  Upon 
this  spindle,  A,  is  carried  a  loop  of  wire,  the  two  terminals  of 
which  are  connected  to  the  two  drums  carried  on  the  forward 
end  of  A.  The  metal  of  these  drums,  as  indicated  in  the  cut,  is 
insulated  from  A,  so  that  all  the  electric  current  generated  by  the 
machine  may  be  taken  up  by  the  brushes,  B\  B\  It  is  obvious 
that,  when  the  spindle,  A,  is  rotated  in  the  direction  of  the  arrow 
at  the  top  of  the  cut,  the  double  loop,  CC,  will  cut  through  the 
lines  of  force,  indicated  by  the  dotted  lines  between  N  and  S. 
Since,  therefore,  these  lines  of  force  have  a  more  direct  path  be- 
tween the  two  poles,  when  the  loop,  CC,  is  in  a  horizontal  posi- 
tion than  when  it  is  in  a  vertical  position,  as  shown  in  the  cut, 
it  follows  that  the  momentary  current  induced  in  the  circuit 
formed  by  brush,  B1,  loop  C,  brush,  B2,  and  the  outside  circuit 
wire,  E,  connecting  the  two  brushes,  will  constantly  vary  in 
strength,  and  also  in  direction  of  movement,  as  the  two  parts  of 
the  loop  are  moved  towards  and  from  the  poles,  N  and  v$\  Since 
the  direction  of  the  current  must  constantly  fluctuate  with  the 
movement  of  the  armature  loops,  CC,  it  follows  that  the  current 
delivered  to  the  outside  circuit,  E,  through  the  two  brushes,  will 
be  an  alternating  current,  which  is  to  say,  one  flowing  first  in 
one  direction  and  then  in  another,  the  potential  varying  with  the 
direction  of  flow.  In  order  to  make  the  current  flow  constantly 
in  one  direction,  it  is  necessary  to  use  a  collector  or  commutator, 
the  construction  of  which  will  be  explained  in  place.  Without 
»this  all  dynamo  currents  would  be  alternating. 

The  armature  of  a  practical  dynamo  or  motor  differs  from  the 
simple  loop  shown  in  the  figure  just  mentioned,  principally  in 
the  fact  that  a  large  number  of  such  loops  are  mounted  on  a 
single  rotating  spindle,  so  that  the  magnetic  lines  of  force  are 
cut  through  a  correspondingly  larger  number  of  times  in  a  given 
period,  with  the  result  that  the  poles  are  shifted  at  a  much  higher 
frequency,  and  the  alternations  of  the  produced  current  are  much 
more  rapid, 


440  SELF-PROPELLED    VEHICLES. 

The  Essential  Parts  of  Dynamos  and  Motors. — The  essen- 
tial parts  of  a  dynamo  generator  and  also  of  an  electric  motor 
are: 

(1)  The  field  magnets  constructed  like  ordinary  electro-mag- 
nets, and  having  two  or  any  even  number  of  opposed  poles  with 
their  windings  connected  in  series. 

(2)  The  armature  rotating  between  the  fields,  so  as  to  cut  the 
lines  of  magnetic  force. 

(3)  The  pole  pieces,  which  are  the  exposed  ends  of  the  magnet 
cores. 

(4)  The  commutator  or  collector. 


FIG.  334.  -Diagram  of  a  Dynamo  Electrical  Generator,  arranged  for  producing  an  alter- 
nating current,  showing  the  constructional  and  operative  features.  Here  N  and  S 
are  the  positive  and  negative  poles  of  the  field  magnets,  between  which  the  lines  of 
force  are  shown  by  the  dotted  lines.  A  is  the  armature  spindle;  B1  and  B2,  the 
brushes  bearing  on  the  ring  drums:  C,  the  coil,  or  winding,  of  the  armature;  E,  the 
outside  circuit  to  which  the  current  is  supplied. 

(5)  The  brushes  which  rest  upon  the  cylindrical  surfaces  of 
the  commutator,  and  as  the  terminals  of  the  outside  circuit,  take 
up  and  deliver  the  current  generated  in  the  coils  of  the  armature. 

The  Varieties  of  Dynamo-Generators. — There  are  a  number 
of  species  of  dynamo,  discriminated  according  to  the  use  for 
which  they  are  intended,  the  arrangement  of  the  armatures,  the 
winding  of  the  field  magnets,  and  the  kind  of  current  they  are  in- 
tended to  produce.  For  general  purposes,  however,  we  may 
discriminate  three  familiar  forms  of  dynamo,  according  to  the 
system  adopted  in  the  winding  of  the  field  magnets ;  these  are : 

(i)  Series-wound  dynamos,  in  which  the  two  poles  of  the  mag- 


DYNAMO  AND   MOTOR   CONSTRUCTION. 

net  are  wound  with  a  few  turns  of  a  heavy  low  resistance  wire, 
one  terminal  of  which  is  connected  to  one  of  the  brushes,  moving 
thence  entirely  around  both  pole  cores,  thence  to  the  outside  line 
and  back  through  the  other  brush. 

(2)  Shunt-wound  dynamos  are  wound  in  the  same  fashion  as 
the  series-wound,  with  the  exception  that  the  pole  cores  are 
wound  with  a  large  number  of  turns  of  high  resistance  wire,  the 
field  windings,  however,  forming  a  shunt-circuit  from  the  main 
outside  circuit,  which  has  its  terminals  at  the  two  brushes  bear- 
ing on  the  armature.  The  terminals  of  the  field  magnets  are  also 
connected  to  the  brushes. 


FIG.  335.— A  Typical  Dynamo-Electrical  Generator,  with  parts  lettered.  A,  the  arma- 
ture; B,  B,  the  brushes;  C,  the  commutator;  E,  E,  the  windings  of  the  field  magnets: 
M,  the  pole  piece  of  the  salient  field  magnet;  F,  F,  bearings  of  the  armature  spindle; 
L,  L,  the  lead  wires;  P,  the  pulley;  T,  T,  terminal  connections  of  the  outside  circuit. 

(3)  Compound-wound  dynamos  combine  the  features  of  both 
the  series  and  shunt-wound  machines,  having  the  field  magnets 
double-wound  with  (a)  a  few  turns  of  heavy  low  resistance  in- 
sulated wire  connected  to  circuit  as  in  the  series-wound  dynamos, 
and  (b)  a  second  winding  arranged  precisely  as  in  a  shunt-wound 
dynamo. 

Shunted  Field  Windings,  Their  Use  —The  object  of  using  a 
shunted  circuit  for  the  windings  of  field  magnets  is  that  the  ma- 
chine may  more  readily  excite  its  own  fields  at  starting,  and  that 


442  SELF-PROPELLED   VEHICLES. 

the  current  may  be  produced  before  the  rotating  armature  has 
fully  taken  up  its  speed.  Some  dynamos  have  their  fields  excited 
by  a  separate  source  of  electrical  energy,  in  which  case  the  mag- 
net windings  are  not  connected  to  the  brushes'  ends,  on  the 
armature,  but  direct  to  the  terminals  of  the  outside  source  of 
electrical  energy.  As  a  usu?l  thing,  however,  it  is  unnecessary 
to  use  a  separate  source  of  current,  for  exciting  the  magnetic 
fields,  since  there  is  a  sufficient  amount  of  residual  magnetism, 
acting  between  the  poles  of  the  magnets,  to  start  the  generation 
of  electrical  energy,  as  soon  as  the  armature  begins  to  rotate. 

Residual  Magnetism  and  Current  Generation. — This  residual 
magnetism,  which  is  a  familiar  property  of  an  electro-magnet, 
that  has  once  been  magnetized,  of  course,  has  very  weak  lines 
of  force  at  the  beginning  of  the  rotation,  but  these  weak  lines, 
being  cut  through  by  the  coils  of  the  armature,  are  able  to  pro- 
duce a  small  amount  of  E.  M.  P.,  which  sends  a  minute  current 
through  the  windings  of  the  field  magnets,  in  consequence  of 
which  both  the  E.  M.  F.  and  the  field  currents  are  constantly 
increased  until  the  rotation  of  the  armature  has  reached  its 
maximum  speed.  At  this  point,  also,  the  output  of  the  electrical 
energy  has  attained  its  highest  point. 

Construction  of  a  Practical  Armature. — The  armature  of  a 
dynamo  or  motor  consists  of  a  drum  or  ring  forming  a  core  and 
support,  upon  which  a  number  of  coils  of  insulated  copper  wire 
are  wound  in  the  same  general  fashion  as  has  been  shown  in 
connection  with  the  ideal  simple  dynamo  already  mentioned. 
The  drum  or  ring  forming  the  supporting  core  is  attached  to 
the  rotating  spindle  by  a  spider  or  key.  The  latter  attachment 
is  universally  used  with  drum  armatures.  The  most  usual 
method  of  constructing  armature  cores  for  dynamos  is  to  build 
them  up  by  placing  together,  face  to  face,  a  number  of  thin 
discs  of  soft  sheet  iron,  which  are  insulated  one  from  the  other 
by  suitable  varnish  or  enamel.  ,  The  circumference  of  each  of 
these  discs  is  toothed  or  serrated,  so  that  when  a  number  of 
them  are  placed  together  the  cylindrical  armature  body  has  a  cor- 
responding number  of  deep  grooves  running  in  its  length.  Into 
these  grooves  the  insulated  wire  of  the  winding  is  inserted.  The 
greater  the  number  of  the  teeth  in  the  circumference  of  the  arma- 


DYNAMO  AND   MOTOR    CONSTRUCTION.  443 

ttire  drum,  the  smaller  the  danger  involved  in  the  production  of 
eddy  currents,  which  are  a  troublesome  source  of  overheating 
and  other  derangements  of  the  machine.  It  is  essential  that  the 
cores  of  the  rotating  armature  should  be  composed  of  the  softest 
iron  in  order  that  the  greatest  magnetic  permeability  may  be  ob- 
tained, since  the  body  of  the  armature  forms  an  integral  part 
of  the  circulation. 

The  Commutator  and  Its  Use. — The  commutator  of  the 
dynamo  or  motor  is  one  of  the  most  essential  elements  in  the 
generation  and  use  of  the  current.  Its  function  is  to  collect  the 
current  produced  by  the  cutting  of  the  lines  of  magnetic  force,  so 
as  to  cause  them  all  to  concur  to  a  desired  result,  transforming 
what  would  naturally  be  an  alternating  current  into  a  direct  cur- 
rent. As  usually  constructed,  the  commutator  consists  of  a  num- 
ber of  L-shaped  metal  pieces,  which  are  so  formed  that  when 
one  arm  of  each  piece  is  connected  to  the  insulating  disc  at  the 
end  of  the  armature  drum,  the  other  arm  will  constitute  one  seg- 
ment of  the  cylinder  arranged  around  the  armature  spindle.  In 
general,  the  commutator  is  formed  of  alternating  sections  of  con- 
ducting and  non-conducting  material,  running  lengthwise  to  the 
axis,  upon  which  it  turns.  Each  segment,  as  we  have  already 
seen,  constitutes  the  point  of  connection  between  two  sections 
of  the  armature  winding ;  it  is  thus  possible  to  collect  the  currents 
induced  in  the  winding  at  the  desired  point,  for  although  the 
effect  of  the  magnetic  induction  upon  the  windings  of  the  arma- 
ture naturally  tend  to  produce  an  alternating  current,  as  already 
suggested,  there  are,  as  will  be  subsequently  explained,  certain 
points  in  the  rotation  of  the  armature  at  which  the  induced  cur- 
rents invariably  move  in  one  direction,  owing  to  the  permanence 
of  the  magnetic  conditions  at  those  points.  These  points  are 
known  as  the  neutral  points,  or  points  of  commutation,  and  in 
order  that  the  direction  of  the  current  sent  over  the  outside  cir- 
cuit may  be  perfectly  constant,  the  brushes  which  form  the  ter- 
minals of  that  circuit  are  here  placed  upon  the  commutator.  In 
other  words,  the  brushes  are  so  arranged  that  they  will  bear  upon 
the  conducting  segment  of  the  commutator  at  exactly  the  neutral 
point  in  the  rotation  of  the  armature.  These  neutral  lines  are 
situated  at  either  extremity  of  its  determined  diameter  of  com- 
mutation, which  diameter  is  theoretically  at  right  angles  to  the 


444 


SELF-PROPELLED    VEHICLES. 


direction  of  the  magnetic  lines  of  force,  as  estimated  for  a  two- 
pole  magnet,  and  would  be  in  that  position  practically  but  for 
the  magnetic  lag,  which  slightly  varies  the  angle.  The  number 
of  segmental  bars  on  the  cylindrical  end  of  the  commutator  is 
naturally  dependent  upon  the  scheme  of  winding  adopted  on  the 
armature,  and  the  number  of  sections  into  which  it  is  grouped. 
In  general,  an  increase  in  the  number  of  segmental  bars  dimin- 
ishes the  tendency  to  spark  and  lessens  the  fluctuations  of  the 


FIG.  336.  — "  Columbia  "  Electric  Runabout.  This  carriage,  weighing  about  1,900  pounds, 
has  a  traveling  radius  of  about  forty  miles  per  full  charge  of  battery,  and  a  maxi- 
mum speed  of  thirteen  miles  per  hour. 

current.  The  increase  in  the  number  of  bars,  however,  has  fixed 
limits  for  several  reasons.  In  the  first  place,  principally  in  large 
machines,  a  great  increase  in  the  number  of  bars  has  a  tendency 
to  increase  the  voltage  of  the  dynamo  beyond  the  safe  limit.  In 
smaller  dynamos,  trouble  speedily  arises  from  the  fact  that  each 
bar  becomes  so  thin  that  a  brush  of  proper  thickness  to  collect 
the  current  would  lap  or  bridge  over  more  than  two  of  them  at 
once. 


CHAPTER    TWENTY-SEVEN. 

THE   OPERATION   OF   ELECTRICAL  GENERATORS   AND   MOTORS. 

Conditions  of  Dynamo  Operation. — The  dynamo  electrical 
generator  is  a  very  sensitive  and  delicately  organized  machine, 
demanding  for  its  efficient  operation  perfect  adjustment  of  its 
various  parts  and  a  constant  watchfulness  for  any  symptoms  of 
dynamo  disease,  overheating  or  sparking,  or  any  of  the  results 
usually  following  imperfect  adjustment  or  careless  handling. 
These  conditions,  however,  need  not  be  enlarged  upon  here, 
since  we  are  concerned  only  with  the  essentials  of  construction 
alike  to  the  dynamos  and  motors,  and  with  the  general  principles 
upon  which  the  generation  and  use  of  the  electrical  current  de- 
pend. 

As  already  stated,  the  operation  of  a  self-excited  dynamo  is 
largely  indicative  of  the  principles  upon  which  it  operates :  The 
cutting  of  the  lines  of  the  residual  magnetism  between  the  cores 
of  the  field  magnets,  the  production  of  induced  currents  in  the 
coils  of  the  armature,  and  their  transmission  through  the  circuit 
of  the  field  magnet  windings,  where  they  are  efficient  in  increas- 
ing the  magnetism  of  the  cores,  also  the  E.  M.  F.  output  of  the 
machine,  as  the  rotation  of  the  armature  approaches  the  maxi- 
mum speed. 

The  Polarization  of  the  Armature. — The  usual  rule  applying 
to  the  efficient  ope-ration  of  a  dynamo  is  that  the  E.  M.  F.  pro- 
duced is  in  proportion  to  the  number  of  turns  of  wire  wound 
about  the  armature,  and  within  definite  limits  also  to  the  speed 
of  its  rotation.  The  result  of  the  rotation  of  the  dynamo  arma- 
ture is  to  produce  a  number  of  reactions  between  its  windings 
and  the  magnetic  field,  with  the  result  that  the  armature  itself  be- 
comes a  magnet,  being  constantly  polarized  at  certain  definite 
points  in  its  path  of  rotation.  According  to  the  accepted  rule  of 
magnetic  induction,  the  tendency  is  to  produce  poles  in  the  arma- 
ture at  right  angles  to  the  lines  of  force,  but  since  the  neutral 
points,  theoretically  situated  on  the  same  diameter,  are  points  of 
contact  between  the  brushes  and  the  commutator,  where  the  cur- 

445 


446 


SELF-PROPELLED    VEHICLES. 


rent  leaves  and  re-enters  the  winding  of  the  armature,  it  will  be 
found  that  the  armature  is  really  transformed  into  two  separate 
adjacent  magnets,  having  two  north  and  two  south  poles,  on 
either  side  of  the  diameter  of  commutation.  These  double  pules, 
practically  operating  as  a  single  pole,  at  the  two  extremities  of 
the  given  diameter,  act  to  produce  the  great  distortion  of  the 
lines  of  magnetic  force,  which  follow  the  rotation  of  the  arma- 
ture. As  shown  in  an  accompanying  diagram,  these  lines  of 
force  are  twisted  into  an  oblique  direction.  This  result  is  largely 
due  to  the  fact  that  the  polarity  of  the  armature  is  not  symmetri- 
cal with  that  of  the  field  magnets.  Were  the  brushes  placed  at 
any  other  point  than  the  extremities  of  the  diameter  of  commu- 


'.AYS:-" 


FIG.  337.— Diagram  of  the  Polarization  of  a  Rotating  Dynamo  Armature  of  the  Ring 
Type,  showing  directions  of  the  lines  of  force  and  of  the  induced  current. 

tation,  the  result  would  be  short-circuiting  of  the  armature  coil. 
This  distortion  of  the  magnetic  field,  which  is  an  important  agent 
in  the  production  of  the  current,  must  be  regarded  as  the  re- 
sultant of  the  two  induced  polarities  of  the  armature,  one  of 
which  is  due  to  induction  from  the  field ;  the  other  to  induction 
from  its  own  windings.  It  marks  the  fact  that,  in  the  process 
of  shifting  the  neutral  points  as  the  armature  rotates,  the  induced 
polarities  are  continued,  with  decreasing  effect  to  be  sure,  hence 
continuing  to  exert  an  attractive  or  repelling  reaction  upon  the 
field  magnets. 

As  shown  in  an  accompanying  figure  showing  the  polarization 
of  the  rotating  armature,  it  will  be  seen  that  the  current  pro- 


ELECTRICAL  DYNAMOS  AND   MOTORS.  447 

duced  in  the  armature  windings  are  moving  in  two  different  di- 
rections between  the  contacts  of  the  brushes.  Entering  at  the 
north  poles  of  the  armature,  their  direction  is  through  the  wind- 
ings, down  either  side  to  their  exit  at  the  south  poles.  These 
two  oppositely  moving  currents,  flowing  between  the  north  and 
south  poles  of  the  armature,  which  is  to  say  between  the  nega- 
tive and  positive  brushes,  respectively,  act  upon  the  body  of  the 
armature  after  the  manner  of  a  current  flowing  in  the  windings 
of  an  electro-magnet,  or  through  the  helical  portion  of  a  solenoid. 
The  result  is  that  an  induced  current  is  set  up  in  the  armature  it- 
self, which,  according  to  the  rule  above-mentioned,  moves  at 
right  angles  to  the  direction  of  the  inducing  current  in  the  wind- 
ings. 


FIG.  338.  -Diagram  of  the  Distortion  of  the  Lines  of  Magnetic  Force  as  they  pass  through 
the  Body  of  a  Rotating  Dynamo  Armature. 

Principles  of  Electrical  Hotor  Operation. — The  foregoing 
discussion  of  the  dynamo  electrical  generator  is  included  in  this 
work,  in  order  to  prepare  the  reader  for  a  better  understanding 
of  the  electrical  motor,  for,  as  already  stated,  the  electrical  motor 
is  the  exact  opposite  of  the  dynamo  in  all  matters  touching  its 
practical  operation.  This  means  that  a  typical  dynamo  may  be 
run  as  a  motor,  with  no  other  alterations  than  changing  the  po- 
sition of  the  brushes  to  the  negative  lead. 

The  respective  action  of  a  motor  and  a  dynamo  may  be  un- 
derstood from  an  accompanying  diagram.  It  shows  a  dynamo 
and  a  motor  coupled  together,  so  that  the  current  generated  in 
the  former  is  driving  the  latter.  As  will  be  seen,  both  the  dynamo 
and  the  motor  are  rotating  right-handedly,  thus  generating  an 


448 


SELF-PROPELLED   VEHICLES. 


electromotive  force,  tending  upward  from  the  lower  brush  to  the 
higher,  each  upper  brush,  in  this  case,  being  the  positive  terminal 
of  the  circuit.  The  cut  also  shows  that  the  brushes  of  the  dynamo 
are  advanced  in  the  direction  of  the  rotation,  while  the  brushes 
of  the  motor  are  advanced  backward  in  the  opposite  direction. 
The  result  of  this  variation  in  the  arrangement  of  the  brushes  is, 
as  is  also  indicated,  the  electromotive  force  in  the  dynamo,  from 
which  current  is  given  forth,  is  in  the  same  direction  as  the  cur- 
rent, both  moving  from  the  lower  to  the  upper  brush,  up  either 
side  of  the  armature.  In  the  motor,  however,  where  work  is 
being  done,  and  energy  is  leaving  the  circuit,  the  electro- 
motive force  is  in  a  direction  opposite  to  the  current ;  the  former 
moving  from  the  lower  to  the  upper  brush,  the  latter  from  the 


FIG.  339.— Diagram  Showing  the  Operative  Conditions  of  a  Dynamo  Generator  and  Elec- 
trical Motor.    The  machine  on  the  left  is  the  dynamo,  that  on  the  right  the  motor. 

higher  to  the  lower  brush,  as  indicated  in  the  cut  by  the  arrows. 
This  brings  us  to  the  most  essential  practical  difference  between 
the  theories  on  which  the  operation  of  dynamos  and  motors  de- 
pend. 

Comparison  of  Dynamos  and  flotors. — As  already  explained 
in  connection  with  the  dynamo,  the  rotation  of  the  armature  cut- 
ting the  lines  of  residual  magnetism  constantly  tend  to  increase 
the  electromotive  force  of  the  current  conducted  to  the  coils  and 
the  field  magnets,  with  the  result  that  the  E.  M.  F.  of  the  current 
generated  is  constantly  augmented,  as  the  induced  magnetic  lines 
increase  in  number  of  strength  until  the  maximum  is  attained. 


ELECTRICAL  DYNAMOS  AND   MOTORS. 


With  the  motor,  however,  the  current  fed  to  the  circuit  is  im- 
parted partly  to  the  windings  of  the  armature  and  partly  to  the 
windings  of  the  pole  magnets,  with  the  result  that,  both  assum- 
ing polarity,  the  magnetic  action  tends  constantly  to  attract  the 
opposite  poles  of  the  armature,  thus  imparting  a  rotative  move- 
ment. Thus  the  magnetic  drag,  which  in  the  dynamo  acts  in  the 
direction  opposing  rotation,  and  is,  in  fact,  the  reaction  against 
the  driving  force,  is  in  the  case  of  the  motor  the  real  driving  force, 
which  propels  the  revolving  armature,  representing  the  pulling 
influence  which  the  magnetic  field  exerts  upon  the  armature 


FIG.  340.— Heavy  truck  of  the  Vehicle  Equipment  Co.     Carrying  capacity,  4  tons : 
speed,  6  miles  per  hour ;  travel  radius  on  one  charge  of  battery,  25  miles. 

wires,  through  which  the  line  current  is  flowing,  and  also  upon 
the  protruding  metal  portions  of  the  armature  core. 

This  operation  is  in  accordance  with  the  law  relating  to  a  cur- 
rent-carrying wire,  situated  in  a  magnetic  field,  in  accordance 
with  which  it  experiences  a  side-thrust,  as  it  is  called,  which  tends 
to  move  it  forcibly  in  a  direction  parallel  to  itself,  across,  the 
direction  of  the  lines  of  magnetic  force.  This  fact  is  well  illus- 
trated in  Fig.  425,  on  page  545,  in  which  the  large  arrow  is  repre- 
sented as  moving  through  the  coil  of  wire,  carrying  current.  The 
direction  of  the  current  in  the  wire  is  indicated  by  the  small  ar- 
rows, and  the  side-thrust,  or  magnetic  push,  by  the  large  arrow, 


450  SELF-PROPELLED    VEHICLES. 

Action  of  the  Field  Magnets  of  a  Motor. — The  second 
point  to  be  considered  in  the  practical  operation  of  an  electrical 
motor  is  that,  while  the  magnetic  action  of  the  field  tends  to  pro- 
duce a  rotation  in  the  armature,  the  same  rotation,  necessitating 
that  the  armature  windings  cut  through  the  magnetic  lines  of 
force,  tends  to  the  production  of  a  counter  electromojtive  force 
(C.  E.  M.  F.),  which,  as  previously  mentioned,  moves  in  a  direc- 
tion contrary  to  the  direction  of  the  current.  As  may  be  readily 
understood,  the  more  rapidly  the  armature  rotates,  the  greater 
will  be  this  C.  E.  M.  F.,  on  account  of  the  fact  that  a  stronger 
field  is  necessary  for  the  increase  of  speed,  and,  consequently, 


FIG.  341.  —A  Heavy  Vehicle  or  Street-Car  Motor,  with  single  reduction,  showing  working 

parts  in  position. 

that  a  greater  number  of  magnetic  lines  are  produced,  which  the 
armature  must  cut  through. 

Two  facts,  however,  follow  from  this  condition : 

(1)  As  the  armature  revolves  more  rapidly,  there  is  a  dimin- 
ished resistance  to  its  motion,  and  on  account  of  the  increase  of 
C.  E.  M.  F.  less  energy  is  absorbed. 

(2)  When    the  motor  is    working  under    load,  the    armature 
necessarily  revolves  more  slowly,  with  a  consequent  fall  in  the 
generation  of  C.  E.  M.  F.,  and  a  greater  absorption  of  energy. 


ELECTRICAL    DYNAMOS    AND    MOTORS.  451 

The  Speed  and  Torque  of  a  Hotor. — As  may  be  understood 
from  what  has  just  been  said,  the  increase  of  speed  marks  an  in- 
crease of  power  in  an  electrical  motor,  just  as  in  a  steam  or  gaso- 
line engine.  There  is,  however,  another  consideration  relating 
to  the  power  of  a  motor,  and  that  is  the  drag  or  rotative  energy 
brought  to  bear  upon  the  circumference  of  the  pulley  or  spur 
attached  to  the  end  of  the  armature  shaft.  This  electro-dynamic 
force,  which  tends  to  produce  rotation  of  the  shaft,  is  known  as 
the  torque,  which  is  to  say,  the  twisting  power  of  the  motor. 

In  estimating  the  efficient  power  of  a  motor,  we  have,  there- 
fore, to  consider  three  elements  : 

(i)  The  power  measured  in  pounds  weight,  which  originally 
causes  the  rotation  of  the  armature  spindle,  and  which  may  be 
readily  determined  by  experimenting  with  pulleys  of  various 


FIG.  342.— Type  of  General  Electric  Light  Vehicle  Motor,  with  case  open,  showing 
commutator  and  brush  apparatus.  The  pinion  end  head  is  arranged  for  doublo 
reduction.  Both  end  heads  and  gear  housing  are  made  of  aluminum.  Suspension 
by  lugs  to  body.  Capacity,  31^  amperes  at  39  volts ;  1,800  K.  P.  M.  at  full  load. 

sizes,  showing  the  power  to  raise  various  weights,  or  by  a  form  of 
Prony  brake,  somewhat  of  the  same  description  as  is  used  for 
determining  the  efficient  power  of  a  steam  or  gasoline  engine,  as 
has  been  already  described. 

(2)  A  second  element  entering  into  the  determination  of  the 
efficient  power  of  a  motor  is  the  diameter  of  the  pulley. 

(3)  The  number  of  revolutions  per  minute  attained. 

Illustration  of  Torque. — The  operation  of  the  torque  of  a 
motor  may  be  illustrated  by  an  accompanying  diagram,  in  which, 
as  shown,  a  rope  wound  about  the  axis  of  a  pulley,  P,  and  having 
a  weight,  W,  attached  to  it,  is  able  to  cause  the  rotation  of  a 


450  SELF-PROPELLED    VEHICLES. 

Action  of  the  Field  Magnets  of  a  Motor.— The  second 
point  to  be  considered  in  the  practical  operation  of  an  electrical 
motor  is  that,  while  the  magnetic  action  of  the  field  tends  to  pro- 
duce a  rotation  in  the  armature,  the  same  rotation,  necessitating 
that  the  armature  windings  cut  through  the  magnetic  lines  of 
force,  tends  to  the  production  of  a  counter  electromojtive  force 
(C.  E.  M.  F.),  which,  as  previously  mentioned,  moves  in  a  direc- 
tion contrary  to  the  direction  of  the  current.  As  may  be  readily 
understood,  the  more  rapidly  the  armature  rotates,  the  greater 
will  be  this  C.  E.  M.  F.,  on  account  of  the  fact  that  a  stronger 
field  is  necessary  for  the  increase  of  speed,  and,  consequently, 


FIG.  341.  —A  Heavy  Vehicle  or  Street-Car  Motor,  with  single  reduction,  showing  working 

parts  in  position. 

that  a  greater  number  of  magnetic  lines  are  produced,  which  the 
armature  must  cut  through. 

Two  facts,  however,  follow  from  this  condition : 

(1)  As  the  armature  revolves  more  rapidly,  there  is  a  dimin- 
ished resistance  to  its  motion,  and  on  account  of  the  increase  of 
C.  E.  M.  F.  less  energy  is  absorbed. 

(2)  When   the  motor  is    working  under   load,  the    armature 
necessarily  revolves  more  slowly,  with  a  consequent  fall  in  the 
generation  of  C.  E.  M.  F.,  and  a  greater  absorption  of  energy. 


ELECTRICAL    DYNAMOS    AND    MOTORS.  451 

The  Speed  and  Torque  of  a  Hotor. — As  may  be  understood 
from  what  has  just  been  said,  the  increase  of  speed  marks  an  in- 
crease of  power  in  an  electrical  motor,  just  as  in  a  steam  or  gaso- 
line engine.  There  is,  however,  another  consideration  relating 
to  the  power  of  a  motor,  and  that  is  the  drag  or  rotative  energy 
brought  to  bear  upon  the  circumference  of  the  pulley  or  spur 
attached  to  the  end  of  the  armature  shaft.  This  electro-dynamic 
force,  which  tends  to  produce  rotation  of  the  shaft,  is  known  as 
the  torque,  which  is  to  say,  the  twisting  power  of  the  motor. 

In  estimating  the  efficient  power  of  a  motor,  we  have,  there- 
fore, to  consider  three  elements  : 

(i)  The  power  measured  in  pounds  weight,  which  originally 
causes  the  rotation  of  the  armature  spindle,  and  which  may  be 
readily  determined  by  experimenting  with  pulleys  of  various 


FIG.  342.— Type  of  General  Electric  Light  Vehicle  Motor,  with  case  open,  showing 
commutator  and  brush  apparatus.  The  pinion  end  head  is  arranged  for  double 
reduction.  Both  end  heads  and  gear  housing  are  made  of  aluminum.  Suspension 
by  lugs  to  body.  Capacity,  31^  amperes  at  39  volts ;  1,800  R.  P.  M.  at  full  load. 

sizes,  showing  the  power  to  raise  various  weights,  or  by  a  form  of 
Prony  brake,  somewhat  of  the  same  description  as  is  used  for 
determining  the  efficient  power  of  a  steam  or  gasoline  engine,  as 
has  been  already  described. 

(2)  A  second  element  entering  into  the  determination  of  the 
efficient  power  of  a  motor  is  the  diameter  of  the  pulley. 

(3)  The  number  of  revolutions  per  minute  attained. 

Illustration  of  Torque. — The  operation  of  the  torque  of  a 
motor  may  be  illustrated  by  an  accompanying  diagram,  in  which, 
as  shown,  a  rope  wound  about  the  axis  of  a  pulley,  P,  and  having 
a  weight,  W,  attached  to  it,  is  able  to  cause  the  rotation  of  a 


452  SELF-PROPELLED    VEHICLES. 

pulley  through  the  force  of  gravity  exerted  on  the  weight,  W . 
Now  the  efficiency  may  be  determined  by  two  considerations : 
(i)  The  number  of  pounds  in  the  weight,  W,  and  the  diameter  of 
the  pulley,  P.  If,  for  example,  the  weight  is  fifty  pounds,  and  the 
pulley  is  of  the  same  diameter  as  the  shaft  around  which  the  rope 
is  wound,  the  weight,  W,  will  exactly  balance  a  weight  equal  to 
itself ;  if  the  pulley  is  twice  the  diameter  of  the  shaft,  the  weight, 
W,  will  be  balanced  by  a  weight  of  twenty-five  pounds,  and  so  on 
indefinitely ;  the  amount  of  weight  necessary  to  balance  weight, 
W,  being  always  in  inverse  proportion  to  the  difference  in  diam- 
eter between  the  shaft  on  which  it  is  coiled  and  the  pulley,  to 
which  is  attached  the  rope  carrying  the  counter-weight.  This  is 
in  accordance  with  the  law  of  levers,  that  the  power  exerted  on 
the  long  arm  of  a  lever  can  raise  a  weight  as  much  greater  than 
itself,  as  the  long  arm  is  longer  than  the  short  arm,  to  which  the 


FIG.  343 — Diagram  Illustrating  the  Theory  of  Torque. 

latter  weight  is  attached.  Consequently,  if  the  torque  at  the 
shaft  of  a  motor  armature  is  equivalent  to  100  pounds  for  that 
diameter,  it  can  exert  a  power  of  only  fifty  pounds  with  a  pulley 
of  twice  the  diameter  of  the  spindle,  and  of  only  twenty-five 
pounds  with  a  pulley  of  four  times  the  diameter  of  the  spindle. 

This  principle  may  be  stated  in  another  manner:  that  the 
pulley  is  capable  of  raising  a  weight  which  is  in  inverse  ratio  to 
the  power  exerted  on  the  spindle  of  the  armature,  as  the  diam 
eter  of  the  pulley  is  greater  than  that  of  the  spindle,  because  the 
work  required  of  it  is  to  raise  its  weight  through  a  vertical  dis- 
tance equal  to  its  own  circumference.  If,  then,  a  pulley  of  I 
foot  circumference  can  raise  a  weight  of  I  pound  to  a  vertical 
distance  of  I  foot,  a  pulley  of  4  feet  circumference  can  raise 
only  i  of  a  pound  through  a  vertical  distance  of  4  feet. 


ELECTRICAL    DYNAMOS   AND   MOTORS.  45  J 

Conditions  of  Motor  Operation. — The  torque  of  a  motor 
armature — being  stated  in  terms  of  pounds  weight  constantly  act- 
ing to  rotate  the  spindle — furnishes  the  first  element  in  all  formu- 
lae for  calculating  the  power  of  such  a  machine.  It  is  evident, 
however,  that  while  it  represents  the  element  of  length,  as  found 
in  the  circumferential  measure  of  the  armature,  and  of  mass  or 
weight  as  found  in  the  total  resistance  to  be  overcome  in  achiev- 
ing a  given  result,  as  found  in  the  load  against  which  the  spindle 
must  revolve,  the  element  of  time  must  be  supplied,  in  order  to 
give  an  idea  of  the  dynamic  stress  constantly  at  work.  In  other 
words,  if  the  torque  necessary  to  move  a  given  load  be  estimated 
as  100  foot-pounds,  the  power  of  the  motor  depends  solely  upon 
the  question  of  whether  that  100  pounds  is  exerted  in  the  unit 
time  or  whether  it  is  a  cumulative  effect  of  a  smaller  energy  act- 
ing through  several  units  of  time.  Thus,  100  foot-pounds  in 
torque  might  accomplish  the  raising  of  a  given  weight  on  a  pulley 
of  given  diameter  in  one  second,  but  10  foot-pounds  would  re- 
quire 10  seconds  to  complete  the  revolution.  Knowing,  therefore, 
that  a  given  effect,  as  for  example,  keeping  a  certain  machine  in 
constant  operation,  demands  an  expenditure  of  3,600  joules,  the 
whole  question  of  power-rating  for  the  motor  depends  on  whether 
this  energy  represents  one  watt-hour  or  ten  o.i  watt-hours. 


Calculating  the  Power  of  a  Motor. — In  estimating  the  power 
of  a  direct  current  electrical  motor  in  terms  of  foot-pounds,  the 
fundamental  formula  gives  the  product  of  the  torque,  as  found 
by  brake  tests,  by  the  angular  velocity.  The  angular  velocity, 
whose  unit  is  one  radian  per  second,  or  such  a  speed  as  shall  en- 
able a  given  point  on  the  circumference  of  the  spindle  to  traverse 
an  arc  equal  to  its  radius — (this  is  described  on  the  unit  angle  of 
57°  17'  44.8"  -f-) — is  found  by  multiplying  the  number  of  revo- 
lutions per  second  by  twice  the  ratio  between  the  circumference 
and  diameter  of  a  circle,  which  is  3.141592,  usually  represented 
by  the  Greek  letter  n(p).  Thus: 

Augular  velocity=6.283i84Xr.  p.  s. 

Then,  with  a  motor  showing  a  torque  of  50  foot-pounds  and 
with  50  revolutions  per  second  of  armature,  the  power  in  foot- 
pounds would  be  found  by  this  formula : 

foot-pounds, 


456  SELF-PROPELLED    VEHICLES. 

In  calculating  the  flux  in  the  core  of  a  magnet  all  formulae 
whatsoever  are  based  upon  considerations  that  can  be  determined 
solely  by  experiment,  among  which  are  the  number  of  ampere 
turns  per  unit  of  length,  the  magnetic  induction,  field  intensity 
and  permeability.  The  fundamental  formula  for  determining 
the  flux  gives  : 

4*  N  I 


which  is  to  say,  the  ratio  between  the  quotient  of  12.566368  and 
the  number  of  ampere-turns  by  the  length  of  the  solenoid,  mul- 
tiplied by  the  cross-sectional  area  of  the  core.  This  formula, 
therefore,  gives  the  product  of  the  magnetizing  force  by  the 
cross-section  of  the  magnet.  The  magnetizing  force  is  theoreti- 
cally equivalent  to  the  length  of  the  pole,  which  may  be  deter- 
mined as  the  quotient  between  the  force  exerted  by  the  pole  and 
the  unit  of  polar  strength.  The  unit  of  polar  strength  or  field 
intensity  is  such  a  repelling  force  as  is  sufficient  to  act  upon  an- 
other unit  pole  of  like  polarity  with  the  strength  of  one  dyne,  or 
fundamental  C.  G.  S.  unit.  The  pole-strength  of  a  stronger,  or 
of  a  weaker,  magnet,  is,  therefore,  equal  to  the  quotient  between 
its  determined  energy  and  the  unit.  The  flux  of  a  magnet  is 
consequently  to  be  found  as  the  product  of  the  pole-strength 
in  dynes  by  the  cross-sectional  area,  although  in  designing  and 
accurately  calculating  motors  and  other  types  of  magnetic  ma- 
chinery the  formula  previously  given,  including  the  number  of 
ampere-turns,  is  necessary. 

Power  in  Terms  of  Electrical  and  Magnetic  Units.  —  In  cal- 
culating the  power  efficiency  of  an  electrical  motor  the  effective 
flux  may  be  experimentally  determined  in  terms  of  watts  (io7  C. 
G.  S.),  as  the  force  with  which  the  field  poles  exert  a  rotative 
pull  upon  the  armature.  In  this  calculation  the  number  of  watts 
realized  in  work  represents  a  given  percentage  t)f  the  watts  de- 
livered at  the  motor  terminals,  the  difference  between  the  two 
figures  having  been  absorbed  in  internal  resistance  during  opera- 
tion. According  to  standard  formulae  : 

„  E.  M.  F.—  C.  E:  M.  F. 
Input  watts^E.  M.  F.  - 

Internal  Resistance. 


ELECTRICAL   DYNAMOS  AND  MOTORS.  457 

,  E.  M.  F.— C.  E.  M.  F. 

Efficient  watts=C.  E.  M.  F. 

Internal  Resistance. 

By  solving  these  equations  we  find  that  the  following  ratios  hold: 

Input  watts  E.  M.  F. 

Efficient  watts  ~~  C.  E.  M.  F. 

However,  the  efficiency  of  a  motor  in  terms  of  watts-output 
depends  upon  the  number  of  revolutions  per  second,  since  the 
stronger  the  flux  the  greater  the  speed.  Thus,  the  efficiency 
in  watts  is  determined  by  the  following  formula : 

Efficient  watts=2  (3.141592)  X  r.  p.  s.  X  T— 

j  j 

in  which  is  found  the  product  of  twice  the  ratio  between  the 
circumference  and  diameter  of  a  circle  by  the  revolutions  per 
second,  by  the  product  of  the  torque  (T)  in  foot-pounds  at  one 
foot  radius  of  the  armature  and  the  ratio  of  watts  to  horse- 
power, reducing  it  to  terms  of  io7  C.  G.  S.  units. 

While  exact  calculations  for  the  design  of  a  motor  to  give  a 
certain  power-effect  involve  the  use  of  more  complicated  fomulse, 
other  authorities  give  readier  average  methods  for  determining 
the  quantities  involved  in  an  active  motor.  Thus  the  reluctance 
per  cubic  unit  of  air  clearance  and  iron  core  may  be  readily 
calculated  for  the  M.  M.  F.  generated  by  a  solenoid  of  a  given 
number  of  ampere-turns.  To  estimate  the  useful  flux  in  an 
armature  core  several  authorities  give  formulae  based  upon  the 
average  magnetic  density  employed  in  motor  armatures.  Ac- 
cording to  average  accepted  figures  the  point  of  magnetic  satura- 
tion of  the  core  is  about  16  kilogausses,  and  the  average  efficient 
flux  about  io  kilogausses.  or  io  maxwells-per-squa.re-centimeter 
of  cross-sectional  area.  To  reduce  to  square  inches,  we  multiply 
by  6.45,  finding  that  the  figure  for  magnetic  saturation  is  about 
103,200  gausses,  and  for  average  effective  flux  about  64,500. 
The  average  effective  flux  may  be  estimated,  therefore,  as  the 
product  of  the  cross-sectional  area  of  the  armature  in  square 
inches  by  the  64,500. 

Knowing,  then,  the  number  of  turns  of  wire,  or  complete  con- 
volutions on  the  motor  armature ;  the  safe  current  strength  in 
amperes  passing  through  the  winding  between  the  brushes,  and 


4:58  SELF-PROPELLED    VEHICLES. 

the  approximate  useful  flux,  the  torque  of  the  motor  in  foot- 
pounds my  be  found  by  the  following  formula  : 

=  foot.pounds. 


85,155,0x50 

Horse-  Power  of  an  Electric  Motor.  —  In  testing  the  horse- 
power capacity  of  a  given  motor  at  .  normal  voltage,  required 
factors  of  torque,  speed  and  radius  may  be  readily  found  —  the 
first  by  brake  test,  the  second  by  tachometer  or  speedcounter, 
and  the  third  by  simple  rule  measurement.  These  quantities 
having  been  determined,  the  horse-power  may  be  found  by  the 
following  formula: 

__  TXRXSX27T  .  . 

H.  P.=  —  —  ,  m   which    F   is   the   torque     in   foot- 

33,000 

pounds  ;  R,  the  radius  of  the  armature  ;  S,  the  speed  in  revolutions 
per  minute;  .2?r  the  constant  6.283.  The  denominator  repre- 
sents the  number  of  foot-pounds  per  minute  making  one  horse- 
power. 


CHAPTER    TWENTY-EIGHT. 

MOTORS    FOR    ELECTRIC    VEHICLES. 

Electrical  Carriage  Motors. — In  several  very  essential  par- 
ticulars the  motors  used  on  electrical  automobiles  are  master- 
pieces of  the  designer's  art.  The  conditions  under  which  they 
are  used  demand  that  they  yield  a  high  percentage  of  efficiency, 
in  spite  of  their  low  power-rating ;  that  they  be  capable  of  operat- 
ing under  several  different  pressures,  and  at  as  many  different 
speeds ;  that  they  be  independent  of  any  such  safety  devices  as 
fuse  wires  and  cut-outs,  and  that  they  give  good  results  at  all 
loads. 

Stationary  motors  are  designed  to  operate  at  certain  maximum 
figures  for  both  load  and  pressure,  and  are  provided  with  auto- 
matic protectors,  which  open-  the  circuit  so  soon  as  the  limit  of 
safety  in  either  particular  is  reached.  The  speed  and  power  out- 
put may  be  regulated  by  adjustable  resistances,  so  as  to  accom- 
modate any  requirement  of  load,  and,  since  such  variations  are 
within  a  moderately  limited  range — always  between  points 
definitely  predetermined — it  is  possible  to  arrange  the  windings 
to  give  the  highest  possible  efficiency. 

An  automobile  motor,  on  the  other  hand,  must  frequently  oper- 
ate at  several  hundred  per  cent,  over  load,  as  when  propelling 
the  vehicle  up  a  steep  incline  or  over  a  heavy  road.  Moreover, 
under  such  conditions,  it  is  impossible  that  fuse  wires  and  cut- 
outs be  used,  since  the  point  of  overload  is  the  very  time  at  such 
full  power  is  required.  The  unusual  strain  put  on  a  motor  on 
such  occasions  is  not  the  only  test  of  endurance  and  capacity, 
since  it  is  frequently  handled  by  a  driver  in  such  manner  as  to 
tax  it  severely ;  in  starting  from  a  standstill  to  ascend  a  heavy 
grade,  to  take  an  unusually  rough  road,  or  to  begin  travel  with 
a  heavy  burden  in  freight  or  passengers,  at  the  highest  voltage. 

In  another  respect  an  automobile  motor  must  possess  excep- 
tional qualities — it  must  combine  strength  and  lightness,  so  as  to 
ensure  good  operation  amid  all  the  jolting  and  vibration  of  travel, 
with  the  fewest  possible  repairs.  Its  working  parts,  particularly 
the  commutator  and  brushes,  must  be  readily  accessible,  so  as  to 


460  SELF-PROPELLED   VEHICLES. 

be  rapidly  inspected  and  repaired,  when  necessary,  and  all  electri- 
cal connections  must  be  as  firm  and  permanent  as  possible.  In 
order  to  prevent  crystallizing,  short-circuiting  and  other  injuries 
to  the  conductors  flexible  cables  are  always  used  between  motors 
and  batteries.  The  requirements  as  to  the  strength  and  firmness 
of  construction  appear  particularly  strenuous,  when  we  consider 
that  the  vehicle  must  most  frequently  be  driven  by  a  person  un- 
skilled in  the  theory,  management  and  repair  of  electrical  ma- 
chinery. 

Among  the  first  mechanical  requirements  in  a  vehicle  motor 
are  those  that  promote  easy  operation.  Thus,  all  rotating  parts 
move  on  ball-bearings,  while  the  end  of  perfect  lubrication  is  se- 
cured by  wick  cups  or  adjustable  compression  oilers.  The  entire 
mechanism  is  carefully  enclosed  in  a  tight  case,  in  order  to  pre- 
vent abrasion  from  dust,  grit,  etc. 

Since,  as  already  stated,  a  vehicle  motor  is  liable  to  be  called 
on  for  sudden  overloads  at  almost  any  time,  its-  working  parts 
must  be  carefully  designed  and  adjusted  to  operate  with  the 
smallest  possible  percentage  of  such  mishaps  as  are  peculiar  to 
electrical  apparatus.  Thus,  it  is  necessary  that  the  insulation 
used  on  all  parts  should  be  of  a  material  capable  of  withstanding 
the  high  temperatures  generated  by  work,  without  danger  of 
burning-out.  Suitable  materials  are  found  in  asbestos  and  mica, 
both  of  which  are  largely  used  in  up-to-date  motor  construction. 
For  the  same  reason,  good  ventilation  should  be  secured  by  even 
more  thorough  facilities  than  are  used  on  any  other  variety  of 
electrical  machine.  The  commutator  is  another  part  requiring 
careful  -attention.  It  should  not  be  so  small  as  to  spark  and 
splutter  on  overloads,  which  is  to  say,  its  bars  or  segments  should 
not  be  so  numerous,  in  proportion  to  its  size,  as  to  involve  spark- 
ing and  overlapping  with  brushes  of  sufficient  diameter  to  carry 
the  required  current. 

This  brings  us  to  a  consideration  of  the  brushes,  which  must 
be  of  such  material  as  to  permit  of  firm  adjustment,  without 
grooving  the  commutator,  and  without  offering  too  high  a  re- 
sistance to  the  current.  In  order  to  secure  the  ends  of  firm  ad- 
justment, without  sparking  or  grooving,  brushes  composed  of 
carbon,  or  some  carbon  combination  are  used  on  many  auto- 
mobile motors.  Carbon  is  particularly  suitable  for  this  purpose, 
since  it  admits  of  permanent  adjustment,  thus  preventing  the 


ELECTRIC   VEHICLE     MOTORS.  461 

many  motor  mishaps  that  come  from  poor  brush  arrangements. 
On  the  other  hand,  its  resistance,  according  to  many  authorities, 
renders  it  unsuitable  to  permit  of  good  work  at  the  low  voltages 
used  on  electric  road  vehicles.  For  this  reason  copper  gauze 
brushes  still  have  their  advocates,  who  claim  superiority,  from  the 
facts  that  lower  resistance  may  be  thus  attained ;  also  that,  when 
properly  constructed,  they  may  be  sufficiently  well  lubricated. 
Such  brushes,  when  disposed  radically  on  the  surface  of  the 
commutator,  can  be  firmly  adjusted  and  offer  sufficient  resist- 
ance to  give  good  commutation.  In  order,  however,  to  avoid 


FIG.  344.— General  Electric  Motor,  Designed  for  Heavy  Vehicle  Use,  with 
sing-le  or  double  reduction.  Capacity,  30  amperes  at  85  volts;  800  R.  P.  M. 
at  full  load. 

the  disadvantages  of  both  carbon  and  copper,  and,  to  secure  the 
good  results  to  be  found  in  either  case,  the  practice  of  using  a 
combination  carbon  and  copper  gauze  brush  is  increasing  among 
motor  manufacturers  and  carriage  builders.  This  latter  may 
be  said  to  be  the  really  typical  construction  at  the  present  time. 

Summary  of  Vehicle  Motor  Requirements. — The  General 
Electric  Co.,  whose  motors  are  widely  used  on  American  electric 
carriages,  summarizes  the  requirements  as  follows : 


462  SELF-PROPELLED    VEHICLES.    . 

"To  attain  the  maximum  possibilities  in  thoroughly  efficient 
and  reliable  apparatus,  the  manufacturer  must  consider  that  com- 
bination which  will  give  proper  structural  strength,  added  to  the 
highest  electrical  efficiency.  A  properly  designed  motor  for  use 
in  connection  with  storage  batteries  must  possess  a  well-sustained 
efficiency  curve  at  overloads,  together  with  fine  speed  and  torque 
characteristics.  The  amount  of  iron  and  copper  used  must  not 
be  stinted,  for  although  generous  proportions  in  this  respect  may 
add  somewhat  to  the  weight  of  the  motor,  this  increase  is  more 
than  counterbalanced  by  the  resultant  improvement  in  the  torque, 
speed  and  efficiency  characteristics  obtained,  besides  decreasing 
the  heating  effect.  It  is  obviously  of  small  importance  if  a  slight 
increment  be  added  to  the  weight,  if  by  so  doing  a  motor  is  able 
to  respond  at  once  to.  extreme  overloads  without  'lying  down' 
or  unduly  taxing  the  batteries,  which  at  best  are  especially  sus- 
ceptible to  injury  by  over-discharge.  Again  it  is  important  that 
the  speed  and  torque  curves  bear  a  proper  relation  to  each  other 
through  all  the  range  of  the  motor's  load.  This  relation  is  a  di- 
rect function  of  the  efficiency  of  the  machine  and  is  only  to  be  ob- 
tained by  a  judicious  liberality  in  the  use  of  high  grade  material. 

"The  mechanical  characteristics  of  the  General  Electric  Co.'s 
automobile  motors  Jhs^ve  received  very  careful  attention.  The 
design  have  been  carried  out  on  the  sturdy  lines  of  the  street 
railway  motor,  particular  care  having  been  exercised  in  provid- 
ing generous  bearings,  rigid  shafts,  simple  and  durable  brush 
fittings  and  commutator  segments  of  such  width  and  depth  as  to 
insure  good  commutation  at  all  loads  and  long  life  of  the  parts. 
The  frames  of  all  General  Electric  automobile  motors  are  made 
of  cast  steel,  and  the  poles  of  laminated  iron.  Field  and  armature 
coils  are  machine- wound  and  thoroughly  taped  and  water- 
proofed. The  armature  shafts  are  tapered  and  provided  with  a 
nut  for  securing  the  pinion." 

Power  Efficiency  of  Vehicle  Motors. — The  power  range  of 
the  average  automobile  motor  is  remarkable.  Thus,  a  motor 
rotated  at  three  horse-power  is  usually  wound  to  develop  at  least 
nine  horse-power,  or  to  take  a  200  per  cent,  overload  at  the  high- 
est voltage.  Few  reliable  authorities  claim  a  higher  capacity  than 
this.  However, as  stated  by  one  manufacturer,  a  motor  for  a  2,000- 
pound,  two-passenger  runabout,  rated  at  2l/2  horse-power,  con- 


ELECTRIC    VEHICLE     MOTORS.  463 

sumes  6,800  watts  in  ascending  an  n  per  cent,  grade  at  7  miles 
per  hour,  although  no  more  than  360  watts  are  required  to  pro- 
pel the  carriage  on  an  even  asphalt  roadway  at  8^2  miles  per 
hour.  These  figures  represent  an  effective  power-range  of  be- 
tween' l/2  horse-power  and  over  9  horse-power.  There  seems 
to  be  some  uncertainty  as  to  the  precise  power-rating  of  car- 
riage motors,  but,  as  matter  of  fact,  they  are  wound  to  develop 
the  highest  constant  power-output  at  the  highest  voltage  (80 
volts)  used,  with  a  high  overload  capacity  for  short  spurts,  as  in 
hill-climbing,  etc. 

Operation  of  a  Series  Motor. — The  motors  used  on  electric 
carriages    are    generally    series-wound,    that    type    having    been 


FIG.  345.  FIG.  346. 

FIG.  345.— General  Electric  Siemens-Halske  Type  of  Vehicle  Motor.  Four- 
pole,  cylindrical,  laminated  fields.  Capacity,  16  amperes  at  80  volts;  1,000 
R.  P.  M.  under  full  load. 

FIG.  346.—  General  Electric  Motor  for  Medium-weight  Vehicles.  Capacity, 
16  amperes  at  85  volts;  850  R.  P.  M.  at  full  load. 

found  very  well  adapted  to  most  ordinary  requirements,  and  from 
many  points  of  view  the  most  efficient  in  operation.  It  also  pos- 
sesses the  valuable  characteristics  of  automatically  adjusting  the 
consumption  of  power,  as  it  were,  to  the  load.  Thus,  at  a  light 
load  it  will  take  small  current,  while,  as  the  resisting  torque  on 
the  machine  increases,  power  sufficient  for  demands  is  constantly 
absorbed,  thus  enabling  the  motor  to  take  extreme  overloads  with 
high  efficiency.  It  is  wasteful,  however,  at  very  light  loads,  as 
in  descending  hills.  Since,  in  a  series  motor,  the  total  internal 
resistance  is  equal  to  the  sum  of  the  armature  resistance  and  the 
field  resistance,  it  follows  that  the  current  is  the  same  under  an 


464  SELF-PROPELLED   VEHICLES. 

even  load  at  any  speed,  and  that  the  torque  is  in  nearly  direct 
proportion  to  the  current.  At  a  light  load,  with  a  small  current, 
the  rotative  speed  of  the  armature  is  comparatively  great,  and, 
owing  to  the  generation  of  a  high  C.  E.  M.  F.,  cuts  down  the 
current  fed  from  the  mains,  in  proportion  to  the  difference  be- 
tween the  impressed  voltage  and  the  internally  generated  voltage. 
Two  things  follow,  therefore ;  that  the  efficiency  is  reduced  at 
high  speeds,  and  that  it  is  reduced  at  light  loads.  With  a  heavy 
load,  reducing  the  speed,  the  efficiency  is  correspondingly  in- 
creased. Consequently,  the  most  conspicuous  problem  before 
the  practical  motor-designer  is  how  to  produce  a  motor  that  will 
give  a  power-output  proportionate  to  the  weight  of  the  motor, 
and,  at  the  same  time,  rotate  its  armature  at  a  comparatively  low 
speed.  This  principle  is  amply  demonstrated  in  the  familiar  fact 
that  a  motor,  developing  a  low  speed  at  a  given  power,  is  capable 
of  being  wound  a  higher  voltage  and  can  take  large  overloads, 
while  .one  developing  an  unusually  high  speed  per  power  unit 
it  capable  of  small  efficiency  at  any  load.  It  may  thus  be  seen 
that  an  increase  of  load,  or  resisting  torque,  acting  to  reduce  the 
speed  of  armature  rotation,  will  cut  down  the  C.  E.  M.  F.,  and, 
rendering  a  greater  pressure  available,  will  permit  a  greater  cur- 
rent to  flow  in  the  windings,  with  the  result  of  creating  a  greater 
flux,  and,  consequently,  also,  a  greater  power  effect.  This  con- 
dition is  explained  by  a  simple  application  of  Ohm's  law.  Thus, 
if  the  electrical  resistance  of  a  given  armature  winding  be  i  ohm 
and  the  pressure  between  the  mains  is  20  volts,  the  current 
strength  would  normally  be  ^o  amperes.  Supposing,  now,  that 
the  C.  E.  M.  F.  generated  when  running  free  be  equal  to  12  volts, 
the  effective  pressure  will  be  represented  by  the  difference  be- 
tween 20  and  12,  or  8  volts,  thus  reducing  the  current  to  8  am- 
peres. As  a  general  statement  of  the  principle  involved,  it  may 
be  asserted  that  an  increase  in  the  resistance  of  the  armature 
winding — by  using  a  large  number  of  fine  wire  turns — involves 
a  large  generation  of  C.  E.  M.  F.  for  given  rates  of  speed,  and, 
consequently,  a  large  drop  in  both  pressure  and  speed  under  load. 
If,  on  the  other  hand,  the  armature  resistance  be  small — the  wind- 
ing consisting  of  comparatively  few  turns  of  coarse  wire — a  given 
C.  E.  M.  F.  would  involve  a  correspondingly  higher  speed  for  its 
generation,  while  a  far  larger  proportionate  current  and  torque 
would  result  with  given  decrease  in  the  speed  of  rotation. 


ELECTRIC   VEHICLE   MOTORS. 


465 


466 


SELF-PROPELLED    VEHICLES. 


Speed  and  Output  of  Power. — It  seems  evident  that  increase 
in  pressure,  involving  high  speeds  at  small  loads,  entails  a  corre- 
sponding loss  of  efficiency — judging  this  as  the  difference  be- 
tween the  input  and  output  in  watts  or  kilowatts — thus  enabling 
us  to  assert  that  the  best  efficiency  of  the  motor  and  the  greatest 
economy  of  current  are  both  attained  by  using  low  pressure  at 
light  loads,  and  raising  the  pressure  only  with  the  increase  of 
load.  Such  a  rule  is  limited,  of  course,  by  considerations  of  the 
motor's  construction,  and  the  range  of  current  strength  to  be 
obtained  in  its  windings  with  definite  variations  of  pressure.  If, 
therefore,  the  armature  of  a  given  motor  is  wound  with  1,000 


FIG.  348.— The  "Lundell"  Octagon  Four-pole  Motor,  with  case  open,  showing 
parts.  Laminated  field  magnets  and  armature  core.  For  vehicle  use 
ranging  between  2.5  and  15  horse  power,  wound  for  80  volts.  At  this 
pressure  the  2.5  horse  power  takes  28.5  amperes;  the  5  horse  power,  55 
amperes;  the  10  horse  power,  110  ampers;  the  15  horse  power,  160  amperes. 

complete  convolutions  of  wire,  representing,  say,  a  resistance  of 
5  ohms,  it  will  carry  a  current  of  16  amperes  at  80  volts,  of  8 
amperes  at  40  volts,  and  of  4  amperes  at  20  volts,  giving  for  the 
three  variations  of  pressure,  16,000,  8,000  and  4,000  ampere  turns, 
respectively.  The  figure  for  flux  will  fall  proportionately,  giving 
a  smaller  power  effect,  and  an  efficiency-rating  inversely  propor- 
tionate to  the  speed  of  armature  rotation. 

Motors   with    Reducing   Gear. — This  practical  situation  has 
been  recognized  by  a  number  of  authorities,  and   several  ex- 


ELECTRIC    VEHICLE     MOTORS.  46T 

pedients  have  been  proposed,  in  order  to  render  possible  a  high 
efficiency  and  economy  in  vehicle  motors.  Thus,  Farman,  a 
French  writer  on  the  subject,  says:  "If  the  E.  M.  F.  is  varied  by 
connecting  up  the  accumulators  in  different  ways,  we  shall  ob- 
tain different  speeds  varying  with  the  electromotive  force.  We 
may  point  out  that,  whatever  the  speed,  the  couple  will  remain 
constant  for  a  certain  intensity  of  current,  as  it  is  propor- 
tional to  the  product  of  the  latter  into  the  flux  of  force  due  to 
the  exciting,  so  that  for  going  up  grades  we  shall  not  have  a 
more  powerful  couple  at  our  service  than  on  the  level,  which 
is  a  great  drawback.  It  would  be  better  to  let  the  motor  revolve 


FIG.  349.— "Herring-bone"  Gear  Transmission  for  Single  Reduction  used  on 
the  Waverley  Electric  Vehicles,  viewed  from  the  front.  The  small 
pinion  is  on  the  motor  shaft,  and  the  hub  of  the  large  gear  forms  the 
differential  drum  on  the  divided  live  rear  axle. 

at  a  high  speed  and  have  a  reducing  gear,  so  as  to  utilize  all 
available  power,  and  yet  travel  at  a  slow  pace. 

"The  method  of  varying  the  E.  M.  F.  simplifies  the  transmis- 
sion to  a  great  extent,  but  it  cannot  be  recommended,  unless  the 
car  has  only  to  travel  over  fairly  level  ground,  when  decrease  in 
speed  always  corresponds  to  decrease  in  the  power  required." 


468 


SELF-PROPELLED   VEHICLES. 


Methods  of  Increasing  Efficiency. — In  spite  of  the  very  evi- 
dent truth  of  many  of  the  statements  here  made,  the  practice  of 
varying  speed  and  power  by  changing  the  couple  of  the  battery 
has  been  retained  by  the  majority  of  electric  vehicle  manufactur- 
ers, among  whom  there  is  a  very  definite  tendency  toward  de- 
signs permitting  of  high  power  outputs  at  low  speeds.  This  end 
is  attained  largely  by  accurately  calculating  the  resistance  of  the 
armature  winding  to  the  pressures  to  be  used,  and,  occasionally, 
by  increasing  the  number  of  the  field  poles.  A  few  manufac- 
turers have  strongly  recommended  the  use  of  shunt  or  com- 


FIG.  350.— Plan  Diagram  of  Single  Motor  Attached  to  Rear  Axle  Through 
"Herring-bone"  Single  Reducing  Gears.  A  is  the  left-hand  section  of 
the  divided  rear  axle;  B,  the  right-hand  section  of  the  rear  axle;  C,  the 
brake  drum;  D,  the  spiral  pinion  on  the  motor  shaft  driving  the  worm 
gear,  I,  on  the  differential;  E,  plug  for  greasing  gears;  F,  set  screw  for 
locking  ball  race;  G,  slot  for  wrench  to  adjust  threaded  ring,  H,  against 
ball  bearings. 


pound-wound  motors,  in  order  to  maintain  the  armature  speed 
practically  constant  for  a  given  voltage  under  all  loads. 


Motor  Development  in  America. — In  desiging  or  estimating 
the  efficiency  of  an  electric  motor  it  must  be  always  borne  in 
mind  that  the  lower  the  power  rating  the  greater  the  speed  of 
armature  rotation.  Thus,  while  a  good  l/2  horse-power  motor 
has  a  normal  speed  of  1,300  revolutions  per  minute  at  full  load, 


ELECTRIC   VEHICLE     MOTORS- 


469 


or  2,600  revolutions  per  output  of  horse  power,  a  I  horse-power 
motor  has  a  normal  speed  of  only  1,000  revolutions  per  minute, 
under  load  a  5  horse-power  motor,  but  900  revolutions,  or  180 
revolutions  per  horse-power  output ;  higher  powered  motors  have 
even  lower  speeds.  As  can  be  readily  understood,  therefore,  the 
lower  the  horse-power  rating,  and  the  higher  the  speed,  the  lower 
the  efficiency.  Thus,  with  the  speed  of  rotation  above  mentioned, 
the  average  i  horse-power  motor  has  an  efficiency  of  about  72  per 
cent. ;  a  6  horse-power  motor,  of  about  81  per  cent.,  and  no  motor 


FIG.  351.— Plan  Diagram  of  Two  Motors  Working  on   "Herring-bone"   Gears 
to  Two  Sides  of  Divided  Rear  Axle  Without  Differential. 


of  much  over  90  per  cent.  In  comparison  with  these  figures,  we 
may  quote  the  published  statements  of  several  manufacturers  of 
carriage  motors,  as  showing  the  high  state  of  perfection  of  motor- 
design  at  the  present  time  in  America.  Qtie  manufacturer,  the 
Elwell-Parker  Co.,  producing  three  sizes  of  carriage  motor,  rated 
respectively,  at  fy,  il/2  and  2l/2  horse-power,  claims  a  speed  of 
1,200  revolutions  per  minute,  and  a  79  per  cent,  efficiency,  for 
the  first;  a  speed  of  1,050  revolutions,  and  80  per  cent,  efficiency 
for  the  second ;  and  850  revolutions  and  82.5  per  cent,  efficiency 
for  the  third.  These  machines  weigh  83,  115  and  155  pounds, 
arid  measure  complete  with  cases,  respectively,  9^x12  7/io", 


4TO 


SELF-PROPELLED    VEHICLES. 


10  9/10x14^",  11^x17  6/1 6".  The  first  figures  in  each  instance 
are  for  diameters,  the  second,  for  length  of  case,  not  measuring 
the  spindle  at  either  end. 

Shunt  and  Compound  Motors. — With  a  view  to  increasing 
the  efficiency  of  automobile  motors,  several  designers  have  pro- 
posed the  use  of  shunt  and  compound  windings,  whose  advan- 
tages in  several  particulars  have  been  made  apparent  in  other 
branches  of  electrical  activity. 


FIG.     352. — Waverley    Delivery     Wagon,   with    double    motor    equipment,     as 
shown  in  Fig.  351. 

Shunt-wound  motors,  in  which  the  field  coils,  instead  of  being 
in  series  with  the  armature,  are  on  a  shunt  between  the  lead 
terminals,  are  very  largely  used  on  constant-potential  circuits, 
on  account  of  their  ability  to  regulate  the  speed,  maintaining  it 
at  a  virtually  uniform  rate,  in  spite  of  the  increase  in  load  up  to  a 
certain  point.  With  differential-wound  compound  motors  the 
same  effect  of  speed  regulation  may  be  attained,  on  a  constant- 


ELECTRIC    VEHICLE     MOTORS. 


471 


potential  circuit,  by  the  interaction  of  currents  in  a  low-resistance 
winding  in  series  with  the  armature  and  a  high-resistance  coil 
in  shunt.  The  former  coil  as  a  demagnetizer,  causing  the  motor 
to  speed  up  under  increased  load,  by  weakening  the  field,  which 
furnishes  an  offset  to  the  tendency  to  slow  down,  under  such 
conditions,  always  varying  the  magnetic  strength  inversely  to 
the  load.  Of  course,  at  very  excessive  overloads  the  danger  is 
that  the  current  in  the  series  winding  will  completely  neutralize 
that  in  the  shunt,  with  the  result  of  checking  armature  rotation, 
and  often  involving  even  greater  disadvantages. 

Regarding  the  use  of  shunt-wound  motors  in  electric  carriages, 
a  well-known  autombile  authority  writes  as  follows:  ".The  use 
of  shunt  motors  on  street  cars  driven  by  storage  batteries  was 


FIG.  353.— Part  Sectional  Diagram  of  a  Single  Motor,  arranged  for  driving 
both  wheels  through  differential  gear.  A  and  A'  are  the  pinions  of  the 
differential  gear;  B,  the  bevel  gear  of  the  left-hand  road  wheel;  D.  bevel 
gear  on  right-hand  road  wheel;  C,  spur  pinions  driving  internal  gear  on 
road  wheels;  E,  sleeve  on  rotating  through  shafts,  F,  of  pinions,  C 
and  C. 

early  claimed  as  a  great  advantage,  but  most  automobile  motors 
are  series-wound.  This  cannot  continue,  for  the  advantages  of 
shunt  motors  are  too  manifest.  What  better  method  for  braking 
is  there  than  to  drop  the  controller  off  a  notch  or  two,  and,  with 
the  motors  acting  as  dynamos,  turn  the  surplus  energy  back  into 
the  battery?  The  ammeter  provided  on  most  electrically-driven 
vehicles  is  a  perfect  guide  in  doing  this.  The  instrument  should 
be  differential,  and,  as  the  needle  comes  back  to  zero,  notch  by 
notch  may  be  turned  off.  In  hill-climbing,  one  third  and  even 
more  of  the  extra  energy  consumed  can  be  recovered  by  coasting- 
down  the  other  side  with  the  controller  set  a  notch  or  two  below 
the  coasting  speed.  These  well-known  possibilities  of  shunt 


472 


SELF-PROPELLED    VEHICLES. 


motors  could  not  be  fully  attained  on  street  cars,  but  with  auto- 
mobiles the  problem  is  very  easy. 

"Full  field  strength  should  be  used  at  all  times.  The  first  act 
of  the  controller  should  be  to  make  the  field  connections,  and  this 
condition  need  not  interfere  with  the  commutation  of  the  cells. 
The  field  coils  may  be  divided  into  as  many  sections  as  batteries, 
and  each  battery  given  a  section.  This  arrangement  will  not  in- 
terfere with  the  batteries  being  switched  in  any  series  or  multiple 
combination  that  may  be  desired.  In  the  annexed  figure  two 
motors  are  shown  in  diagram,  each  of  which  has  two  field  coils. 
The  battery  is  divided  into  four  sections,  a  very  common  arrange- 
ment, and  each  section  excites  a  field  coil." 

Such  an  arrangement  as  is  here  suggested,  combined  with  a 


FIG.  354.— Diagram    of    Circuit    Arrangements    with    Shunt    Motors,  as    ex- 
plained in  text. 

series  field  coil,  has  evidently  been  put  into  operation  by  one  or 
two  manufacturers.  Of  course,  with  uniformly-wound  shunt 
and  series  coil,  both  fields  are  greatly  excited  at  high  load,  and, 
the  magneto-motive  force  of  both  acting  in  the  same  direction, 
the  energizing  flux  would  be  somewhat  increased,  with  conse- 
quent reduction  of  armature  rotation,  in  developing  the  required 
C.  E.  M.  F.  Proper  adjustment  can  largely  neutralize  the  drop 
in  speed  that  is  liable  to  follow  the  drop  o'f  pressure  in  the  arma- 
ture resistance,  thus  enabling  the  maintenance  of  nearly  constant 
speed  under  nearly  all  loads. 

Operation  of  Compound  Motors. — The  manufacturers  of  a 
well-known  make  of  American  electric  carriage  using  a 
compound-wound  motor  speak  as  follows  of  its  operation :  De- 


ELECTRIC    VEHICLE     MOTORS. 


473 


fining  the  shunt  winding  as  "an  additional  path  for  the  electric 
current  for  the  passage  of  the  lines  of  force,  giving  more  torque 
and  less  speed,"  they  assert  that,  "to  give  greater  impetus  to  the 
motor  and  accelerated  speed  to  the  vehicle,  we  weaken  the  field 
of  the  motor  by  cutting  out  the  shunt  by  means  of  the  shunt  but- 
ton on  the  floor  of  the  carriage.  This  gives  the  maximum  speed 
to  the  vehicle.  The  advantage  of  the  compound-wound  motor 
is  at  once  apparent,  as  the  cutting  out  of  the  shunt  cannot  weaken 


FIG.  355.— Studebaker  Electric  Runabout,  with  Chain  and  Sprocket  Connec- 
tions between  Motor  hung  on  the  Boay  and  the  Rear  Axle.  --.The  ad- 
vantage is  that  the  motor  is  protected  from  the  jars  of  travel-  by  the 
springs. 

the  field  abnormally.  Hence,  the  driver,  if  he  chooses,  may  run 
at  his  maximum  speed  at  will,  without  the  least  injury  to  the 
motor,  but  at  the  expense  of  distance,  by  reason  of  the  more 
rapid  discharge  of  current." 

A  "Recharging"  Shunt  Motor. — Another  American  carriage 
motor  of  the  compound-wound  variety  is  thus  described ;    "It  is 


474 


SELF-PROPELLED    VEHICLES. 


a  well-known  fact  that  the  efficiency  of  a  series  motor  is  very 
low  until  enough  current  flows  through  the  field  coils  of  the 
motor  to  produce  considerable  magnetic  flux,  and  while  a  series 
machine  can  take  extreme  overloads  with  fair  efficiency,  it  is  apt 
to  have  a  low  efficiency  on  good  smooth  ground,  because  the 
work  required  of  the  motor  is  so  small  under  the  latter  condition. 
"The  motor  illustrated  herewith,  as  well  as  its  controller,  is 


FIG.  356.— Chain  and  Sprocket  Double  Reduction  for  Heavy  Trucks.     As  here 
shown,  the  motor  is  hung  above  the  springs,  missing  the  jars  of  travel. 


design-ed  to  overcome  in  a  considerable  degree  the  objections 
noted.  It  is  compound-wound,  and  the  controller  is  so  arranged 
that  the  shunt  field  is  constant  whatever  the  voltage  on  the 
armature  may  be.  The  strength  of  the  shunt  field  is  the  same, 
whether  the  motor  is  running  with  20,  40  or  80  volts.  This  ar- 
rangement makes  it  possible  to  attain  a  very  hi jh  efficiency  at  low 


ELECTRIC    VEHICLE     MOTORS.  475 

loads,  which  is  not  possible  with  a  series  motor.  Another  very 
important  advantage  is  the  saving  of  most  of  the  power  which 
is  usually  wasted  as  friction  in  mechanical  brakes. 

"This  motor  drives  a  carriage  carrying  40  cells  of  battery  at 
about  4  miles  an  hour  on  the  first  speed,  or  about  20  volts  at 
the  brushes ;  the  rate  is  8  miles  an  hour  on  the  second  speed,  with 
40  volts  at  the  brushes,  and  16  miles  an  hour  on  the  third  speed, 
with  80  volts  (the  battery  all  in  series)  at  the  brushes.  The  ad- 
vantages of  the  shunt  winding  may  be  best  shown  by  taking  a 
concrete  example.  Suppose  this  carriage  is  traveling  at  a  rate 
of  about  8  miles  an  hour  and  begins  to  descend  a  grade;  the 
speed  will  be  increased  and  the  C.  E.  M.  F.  of  the  armature 
will  increase.  At  a  rate  of  about  9  miles  an,  hour,  no  current 
will  pass  through  the  armature,  and  when  the  speed  rises  to 
about  9J/2  miles,  the  C.  E.  M.  F.  will  have  still  further  increased, 
so  that  the  motor  becomes  a  generator  and  charges  the  batteries. 
Any  greater  increase  in  the  speed  of  the  carriage  is  impossible, 
because  a  slight  increase  will  very  greatly  increase  the  load  on 
the  motor  by  increasing  the  charging  current. 

"If  it  is  desired  to  descend  the  hill  at  a  lower  rate  of  speed 
than  between  9  and  10  miles  an  hour,  the  controller  can  be  moved 
to  the  first  speed,  and  it  will  be  impossible  for  the  carriage  to 
descend  at  a  higher  rate  of  speed  than  5  miles  an  hour;  and  the 
power  which  would  have  been  wasted  in  the  friction  of  the 
mechanical  brakes  in  descending  the  hill  will  be  used  in  driving 
the  motor  acting  as  a  dynamo  and  charging  the  storage  batteries. 
This  is  also  valuable  in  bringing  the  carriage  to  a  lower  speed  on 
level  roads.  If  the  carriage  is  traveling  at  the  highest  speed  and 
the  controller  is  moved  to  the  second  speed,  the  momentum  of 
the  carriage  drives  the  motor  as  a  dynamo  and  rapidly  charges 
the  battery  until  the  speed  drops  to  8  or  9  miles  an  hour.  When 
the  speed  decreases  so  that  the  batteries  are  no  longer  being 
charged,  the  controller  can  be  placed  at  the  first  speed  and  a 
still  further  charge  of  the  batteries  be  effected.  This  brings  the 
speed  to  about  4^  miles  an  hour." 

The  manufacturers  further  enlarge  on  the  merits  of  their  "re- 
charging motors"  as  follows : 

"A  still  more  important  advantage  over  the  ordinary  series 
motor  is  that  the  average  efficiency  is  higher — particularly  at 
light  loads,  It  is  a  well-known  fact  that  a  carriage  driven  by  a 


476 


SELF-PROPELLED    VEHICLES. 


series  motor  requires  all  of  half  and  probably  two-thirds  of  the 
current,  when  running  down  a  3  per  cent,  or  4  per  cent,  grade,  as 
is  required  when  running  on  a  level.  .The  efficiency  of  a  series 
motor  is  very  low  below  half  load. 

"When  a  carriage  is  running  down  a  l/2  per  cent,  grade,  for 
example,  the  load  is  very  much  -less  than  when-  running  on  a 
level,  but  the  current  required  by  a  series  motor  is  very  little 
less  than  that  required  on  a  level.  On  the  other  hand,  our  motor 
takes  current  strictly  in  proportion  to  the  load,  and  the  saving 
in  current  consumption  is  very  great. 


FIG.  357.— Electric  Brewery  Wagon  of  the  Vehicle  Equipment  Co.  Carrying 
capacity,  5  tons:  speed,  6  miles  per  hour  at  full  load;  travel  radius  on 
one  charge,  25  miles. 

"Due  to  the  two  causes  mentioned,  a  carriage  driven  by  this 
motor  will  travel  from  15  to  40  per  cent,  further  than  the  same 
one  driven  by  an  ordinary  series  motor.  For  instance,  a  carriage 
driven  by  a  series  motor,  built  by  a  well-known  firm,  required 
13  amperes  to  drive  it  down  a  certain  grade  of  about  4  per  cent., 
while  the  same  carriage  equipped  with  one  of  our  motors  and 
controllers,  descended  the  same  grade  and  charged  the  battery 


ELECTRIC   VEHICLE     MOTORS.  '  47T 

20  amperes.  The  change  of  the  machine  from  motor  to  dynamo 
is  entirely  automatic.  It  is  impossible  for  one  sitting  in  the  car- 
riage to  tell  whether  the  battery  is  receiving  current  from  or 
delivering  current  to  the  motor." 

If  the  findings  of  such  experiments  hold  good  for  general  prac- 
tice, the  advantages  of  a  recharging  motor,  as  an  economizer  of 
current,  must  be  evident  on  reflection.  Of  course,  the  recharg- 
ing effected  under  ordinary  conditions  could  scarcely  add  very 
much  to  the  radius  of  travel.  Could  such  a  motor  be  driven  as 
a  dynamo  from  a  separate  source  of  power,  it  is  probable  that 
it  could  recharge  the  battery  at  slow  rate,  provided  that  the  speed 
be  sufficient.  A  motor  of  this  type,  having  a  field  magnet  di- 
ameter of  gl/2  inches  and  a  total  length  between,  ends  of  bearings 
of  13  inches,  gives  il/2  H.  P.  at  1,500  revolutions;  one  of  n^x 
141/6  inches  for  same  dimensions,  gives  2l/2  H.  P.  at  1,200  revo- 
lutions, and  one  measuring  14x18^  inches,  gives  5  H.  P.  at  900 
revolutions. 


CHAPTER    TWENTY-NINE. 

PRACTICAL    POINTS    ON    MOTOR    TROUBLES. 

Electric  Motor  Troubles.— The  following  digest  of  common 
motor  troubles  is  given  by  Mr.  George  T.  Hauchett  in  The  Auto- 
mobile, and  is  re-printed  by  permission : 

"While  it  is  not  necessary  to  be  an  electrician  to  operate  an  elec- 
trically driven  vehicle,  it  is  of  great  advantage  to  know  what  to 
do  when  certain  troubles  occur. 

''Let  us  consider  first  a  single  motor  equipment  provided  with 
a  battery  which  is  connected  in  different  ways  for  the  various 
speeds.  Suppose  an  attempt  is  made  to  start,  and  the  vehicle 
does  not  respond  and  the  ammeter  shows  no  indication.  This 
almost  invariably  means  open  circuit ;  that  is  to  say,  the  path  for 
the  electricity  from  the  batteries  to  the  motors  is  not  closed.  We 
may  find  open  circuits  at  any  of  the  following  points : 

"A.  The  battery  contacts.  They  may  be  and  often  are  so  badly 
corroded  as  to  prevent  the  necessary  metal-to-metal  contact. 

"B.  The  controller.  A  connection  may  be  loose  or  the  fingers 
may  not  make  contact. 

"C.  The  running  plug  may  sometimes  be  out  or  not  making 
proper  contact. 

"D.  The  motor  brushes.  May  have  dropped  out  or  the  tension 
may  be  so  weak  that  they  do  not  make  contact. 

"E.  The  emergency  switch  may  be  open. 

"Leave  the  controller  till  the  last.  It  is  but  a  moment  to  in- 
spect the  other  joints  and  to  discover  the  trouble  in  them  after 
an  hour's  fussing  with  the  controller  is  clearly  a  waste  of  time. 

"If  the  carriage  operates  at  any  of  the  speeds  and  fails  to  oper- 
ate on  the  others,  the  ammeter  needle  falling  to  zero,  the  trouble 
is  almost  certainly  in  the  controller.  The  contact  fingers  that 
are  brought  in  play  at  the  inoperative  speeds  should  be  inspected. 
Often  a  screw  adjustment  or  a  rub  with  a  piece  of  emery  cloth 
will  correct  the  difficulty. 

"If  the  motor  tries  to  start,  but  the  current  is  not  sufficient,  as 
shown  by  the  ammeter,  poor  contact  or  weak  battery  may  be  sus- 
pected. Discharged  battery  will  be  betrayed  by  a  low  voltmeter 

478 


ELECTRICAL  MOTOR   TROUBLES.  479 

indication,  but  if  the  yoltmeter  registers  the  normal  amount, 
poor  contact  should  be  sought.  Any  contacts  which  are  part  of 
the  electric  circuit,  such  as  binding  posts,  brushes,  switch  jaws 
or  controller  fingers  must  be  bright  metal-to-metal  contacts.  If 
they  are  dirty  or  corroded  the  contact  may  be  so  bad  that  the  flow 
of  current  is  seriously  reduced  or  interrupted  altogether. 

"Improper  Connections. — Sometimes  the  absence  of  ampere 
indication  and  no  motion  of  the  vehicle  points  to  a  very  serious 
trouble,  namely,  the  improper  connection  of  the  batteries.  This 
will  be  shown  by  heavy  sparks  at  the  controller ;  in  fact,  heavy 
sparks  at  the  controller,  absence  of  ammeter  indications  and  re- 
fusal of  the  vehicle  to  move,  could  only  be  caused  by  one  other 
difficulty  than  this,  which  will  be  discussed  further  on. 

"When  the  battery  is  not  properly  connected,  the  motion  of 
the  controller  causes  the  sections  of  battery  to  exchange  current 
between  themselves  at  a  ruinous  rate.  The  terminals  of  the  cells 
and  those  to  which  they  should  be  connected  ought  to  be  plainly 
marked,  or,  better  still,  so  constructed  that  it  is  impossible  to 
go  wrong.  If  the  trouble  just  cited  is  the  fact,  one  or  more  sets 
of  terminals  of  the  cells  will  be  found  to  be  connected  to  the 
wrong  wires. 

"If  the  vehicle  fails  to  move  and  the  flow  of  current  as  indi- 
cated by  the  ammeter  is  enormous,  shut  off  the  power  at  once. 
Serious  damage  may  ensue  if  this  is  not  done.  Then  look  to  see 
if: 

"A.  The  brakes  are  on. 

"B.  The  vehicle  is  stalled  or  blocked. 

"C.  The  gears  are  free  and  there  is  no  obstacle  between  the 
teeth. 

"If  the  motor  makes  a  noticeable  attempt  to  move  the  trouble 
is  probably  something  of  this  mechanical  nature. 

"Short  Circuits. — If,  however,  large  current  is  indicated  and 
the  motor  remains  absolutely  inert,  the  trouble  is  electrical,  and 
the  inference  is  that  the  current  does  not  go  through  the  motor 
at  all.  Lift  one  of  the  motor  brushes  and  try  the  vehicle  again. 
If  the  large  current  is  still  indicated,  the  inference  becomes  a 
certainty.  This  trouble  is  known  a.s  short  circuit,  that  is  to  say, 
a  spurious  path  for  the  current  which  deflects  it  out  of  the  motor. 


480 


SELF-PROPELLED    I  'EH1CLES. 


"I 

ill! 


l/wwi 


STOPS 


TURNS  AT 
DOUBLE  SPEED 


H'h 

m 


STOPS 


STOPS 


[AAAA/ 


HMH 


STOPS 


STOPS 


STOPS 


TURNS 


FIG.  358.— Diagram  of  Common  Motor  Troubles,  as  described  in  the  text. 


ELECTRICAL  MOTOR  TROUBLES.         481 

In  the  controller  may  be  sought : 

4 -A.  Foreign  pieces  of  metal  making  contact  between  portions 
of  the  electrical  circuit. 

"B.  Loose  ringers  which  may  make  contact  with  wrong  parts  of 
the  controller  or  with  each  other. 

"C.  Dirt  between  the  fingers  or  contacts. 

"D.  Breaks  in  the  insulation  permitting  the  wires  to  make  con- 
tact with  adjacent  metal  or  with  each  other. 

"If  the  controller  appears  to  be  all  right,  look  in  the  motor  for: 

"A.  Broken  insulation,  allowing  the  bare  wires  to  touch  the 
frame  or  each  other. 

"B.  Dirt  between  contacts  or  between  live  metal  and  the  motor 
frame. 

"C.  Foreign  materials  bridging  contacts. 

"In  such  a  case  it  is  sometimes  of  assistance  to  turn  on  the 
current  for  an  instant.  The  defective  place  may  betray  its  lo- 
cality by  a  smoke  or  spark. 

"If,  when  the  brush  is  lifted,  and  the  vehicle  tried,  the  ex- 
cessive current  indication  disappears,  there  are  but  two  electrical 
troubles  that  are  possible : 

"A.  The  magnet  coils  of  the  motor  may  be  short  circuited. 

"B.  The  ammeter  may  not  be  reading  correctly. 

"The  latter  trouble  is  least  likely ;  the  former  should  be  sought 
first. 

"A  series  motor  with  a  short  circuited  magnet  coil  will  call 
for  a  large  current  but  will  do  nothing  with  it.  Therefore,  exam- 
ine the  magnet  coil  terminals  for  troubles  of  this  .nature. 

"A  short  circuit  may  exist  even  if  the  ammeter  does  not  in- 
dicate it.  In  such  a  case  it  is  usually  found  in  the  controller, 
which  sparks  heavily  when  operated,  although  the  vehicle  does 
not  move.  This  combination  of  phenomena  also  indicates  im- 
proper connection  of  the  batteries,  as  has  been  previously  ex- 
plained. 

"An  excessive  call  for  current  is  accompanied  with  a  drop  in 
the  voltmeter  indication. 

"Two=Motor  Troubles. — With  a  two-motor  equipment  the 
difficulties  that  may  arise  differ  but  little.  A  few  which  are 
peculiar  to  this  type  may  be  mentioned.  Such  motors  are  some- 
times run  in  two  ways.  The  first  notch  connects  the  motors  in 


482  SELF-PROPELLED   VEHICLES. 

series,  while  the  higher  speed  notches  connect  the  motors  in 
parallel.  If  one  of  the  motors  open-circuits  on  a  series  notch, 
the  vehicle  stops,  for  the  entire  motive  circuit  is  broken.  If  it 
open-circuits  on  a  parallel  notch,  that  motor  stops  and  the  other, 
with  its  circuit  to  the  batteries  intact,  continues  to  run  and  may 
cause  the  vehicle  to  make  some  abrupt  and  unexpected  turns.  If 
either  of  the  motors  gets  short-circuited,  the  exact  converse  takes 
place.  If  the  accident  occurs  on  a  series  notch  the  unimpaired 
motor  continues  to  run,  and,  it  may  be  added,  at  nearly  double  its 
previous  speed.  If  it  occurs  on  a  parallel  notch  a  short  circuit  on 
one  motor  constitutes  a  short  circuit  on  the  other  also,  and  if  the 
short  circuit  is  sufficiently  severe  both  motors  will  stop,  even 
though  an  enormous  current  may  be  drawn  from  the  batteries." 


CHAPTER   THIRTY. 

METHODS     OF     CIRCUIT-CHANGING     IN     ELECTRICAL     MOTOR 
VEHICLES,     AND    THEIR    OPERATION. 

Varying   the   Speed   and    Power   Output  of  a  flotor. — The 

methods  employed  to  vary  the  speed  and  power  output  of  an 
electric  vehicle  motor  consist  briefly  in  such  variation  of  the 
electric  circuits  as  will  modify  the  pressure  of  the  batteries  on 
the  one  hand  and  the  operative  efficiency  of  the  motors  on  the 
other.  This  is  a  very  simple  matter  and  may  be  expressed  in 
a  few  words.  As  is  well  known,  there  are  two  general  methods 
of  connecting  up  both  electric  batteries  of  any  description  and 
electric  motors.  They  are  the  series-wiring  and  the  multiple- 
wiring,  or  parallel-wiring.  In  series-wiring,  various  cells  of  a 
galvanic  battery,  or  the  several  units  of  a  battery  of  dynamos, 
are  connected  in  line.  At  one  terminal  of  each  is  the  negative 
pole,  at  the  other  the  positive — each  unit  in  combination  having 
its  negative  pole  connected  to  the  positive  pole  of  the  one  next 
following.  In  the  parallel  method  of  wiring  the  various  units 
are  each  separately  connected  at  their  positive  and  negative  poles 
to  two  lead  wires,  one  of  which  is  the  positive  pole  of  the  battery, 
the  other  the  negative. 

Effects  Obtained  by  Varying  the  Circuits.— Electric  motors, 
lights  and  other  electrically  effected  devices  are  similarly  con- 
nected in  circuits,  either  in  series  or  parallel.  Now,  in  the  mat- 
ter of  circuit  arrangements  on  this  plan,  one  general  principle 
may  be  laid  down,  which  is  that  a  connection  of  a  number  of 
electrical  generators  in  series  involves  an  increase  in  the  power 
pressure  of  the  battery,  which  is  equal  to  the  sum  of  the  individual 
voltages.  Connecting  a  number  of  generating  units  in  parallel 
or  multiple  has  the  effect  of  producing  a  pressure  only  equal  to 
the  voltage  of  one  of  the  units.  Thus,  if  four  generators  of  10 
volts  each  be  connected  in  series,  the  pressure  is  equal  to  40 
volts.  If,  however,  they  be  connected  in  parallel  or  multiple, 
the  pressure  is  equivalent  to  but  TO  volts,  the  effect  in  the  latter 
case  being  the  same  as  if  but  one  unit  were  in  circuit,  so  far  as 

483 


484 


SELF-PROPELLED    VEHICLES. 


the  voltage  is  concerned.  On  the  other  hand,  where  four  motors 
are  connected  in  series  the  efficient  pressure  of  the  circuit  is 
reduced  to  very  nearly  J  for  each  motor,  the  C.  E.  M.  F.,  gen- 
erated by  their  operation,  serving  to  cut  down  the  average  of 
efficiency ;  but  when  four  motors  are  connected  in  parallel,  which 
is. to  say,  bridged  between  the  limbs  of  the  circuit,  the  greatest 
available  pressure  of  the  battery  is  able  to  act  upon  each  one 
of  them. 


FIG.  359.— Diagram  of  the  Controlling  Apparatus  of  a  Columbia  Light  Electric 
Vehicle.  A.  brake  pedal ;  B,  ratchet  retaining  pedal  in  place,  operated  by  left 
foot;  C,  dash  board  ;  D,  body  sill ;  E,  steering  handle ;  F,  controller  handle ;  G, 
rocker  shaft  for  setting  hub  brakes ;  J,  brake  band  on  wheel  hub ;  H,  rear  axle. 

Arrangement  of  the    Batteries  and  Motor   Parts. — In    an 

electric  vehicle  the  storage  batteries  are  arranged  so  as  to  form 
a  number  of  units,  the  circuit  wiring  being  so  arranged  that  by 
the  use  of  a  form  of  switch  known  as  a  controller  the  connec- 
tions may  be  varied  from  series  to  multiple,  or  the  reverse,  as 
desired.  The  same  arrangement  for  varying  the  circuit  con- 
nections is  used  for  the  field  windings,  and,  with  some  manufac- 
turers, for  the  brush  connections  also.  In  the  accompanying 
first  diagram  of  the  connections  of  an  electric  vehicle  this  fact 
is  indicated.  The  dotted  lines  on  each  figure  indicate  the  cir- 


METHODS    OF    CIRCUIT-CHANGING. 


485 


cuits  that  are  cut  out,  or  open,  and  the  full  lines  those  that  are 
active,  or  closed.  In  the  figure  showing  the  first  speed,  we  have 
the  two  units  of  the  battery,  B,  connected  in  multiple,  which 
means  that  the  voltage  is  reduced  to  the  lowest  point.  The 
wire,  C,  connected  to  the  bridge  between  the  positive  poles  of 
the  battery,  leads  the  current  to  the  field  windings,  H  and  /, 
which,  in  this  figure,  are  connected  in  series-multiple,  which 


Z-t?  SP££0 


!/WJW\i 
H/ 


Wjwi 

FIG.  360.  —Diagram  of  the  Circuit-Changing  Arrangements  of  a  Typical  Electrical 
Vehicle.  The  full  lines  in  these  plans  indicate  the  closed,  or  active,  circuits;  the 
dotted  lines  the  open,  or  inactive,  circuits.  As  may  be  readily  understood,  the  whole 
scheme  of  circuit-changing  depends  on  employing  several  different  circuit  con- 
nections between  battery  and  motor,  which  may  be  opened  and  closed,  as  desired. 
Here  A  and  C  are  the  lead  wires  between  battery,  B,  and  motor  brushes,  F  F  and 
G  G,  and  the  field- windings,  H  and  J,  and  wire,  D. 

gives  the  lowest  speed  and  power  efficiency  of  the  motors.  By 
the  wire,  D,  the  current  is  carried  to  the  brushes,  FF  and  GG, 
which,  according  to  this  scheme,  are  permanently  connected  in 
multiple,  the  return  path  to  the  negative  pole  of  the  battery  be- 
ing through  the  wire,  A. 


486  SELF-PROPELLED    VEHICLES. 

In  the  second  figure  of  the  diagram  the  circuit  is  varied  so  as 
to  connect  the  two  units  of  the  batteries,  so  as  to  give  its  highest 
pressure  efficiency.  But,  since  the  field  windings  of  the  motors 
are  also  connected  in  series,  or  in  series-parallel,  as  in  this  case, 
the  efficiency  in  speed  and  power  is  reduced  nearly  one-half. 

In  the  third  figure  the  two  units  of  the  battery  are  connected 
in  series,  which,  as  in  the  former  case,  indicates  the  greatest 
efficiency  in  power  output ;  but  the  field  windings  are  connected 
in  parallel,  which  means  that  the  C.  E.  M.  F:,  generated  by  their 
operation,  is  equivalent  to  the  C.  E.  M.  F.  of  only  one  motor, 
with  the  result  that  the  speed  and  power  efficiency  is  raised  to 
its  highest  point. 

Diagram  of  Battery,  flotor  and  Controller. — In  the  second 
diagram,  illustrating  a  typical  method  of  shifting  the  circuits, 
we  have  the  same  general  scheme  applied,  so  far  as  the  first, 
second  and  fourth  speeds  are  concerned,  the  connections  of  the 
controller  being  laid  out  in  rectangular  form  between  the  broken 
lines.  When  the  controller  is  rotated,  so  that  the  row  of  ter- 
minal points,  A,  B,  C,  D,  E,  F,  G,  are  brought  into  electrical 
contact  with  the  row  of  terminal  points,  on  the  controller,  A',  B', 
C,  D',  E',  F',  G',  we  have  the  first  speed  forward,  which,  as  may 
be  readily  discovered  by  tracing  the  connections  throughout,  in- 
volves that  the  two-unit  battery  is  connected  into  multiple  and 
the  field  windings  of  the  two  motors  in  series.  Tracing  the  con- 
nections indicated  for  the  second  speed,  we  see  that  the  terminal 
points,  A,  B,  C,  etc.,  are  brought  into  electrical  contact  with 
A*,  B2,  C2,  etc.,  and  we  have  the  batteries  in  multiple  and  the 
fields  in  series-multiple.  Tracing  the  connections  indicated  for 
the  third  speed,  we  have  the  terminal  points,  B  and  C,  con- 
nected to  the  terminal  points,  B*  and  C9,  and  the  terminal  points, 
E  and  F,  connected  to  the  terminal  points,  E3  and  Fa,  which 
means  that  the  batteries  are  connected  in  series  and  the  fields 
in  series.  Similarly,  by  tracing  the  connections  for  the  fourth 
spefd,  we  find  the  terminal  points,  B  and  C,  connected  to  ter- 
minal points,  B*  and  C*,  and  the  terminal  points,  D,  E,  F,  G,  in 
electrical  connection  with  the  terminal  points,  D4,  E*,  F4,  G\ 
which  means  that  the  batteries  are  in  series  and  the  fields  in 
multiple.  The  connections  between  the  battery,  the  armature 
brushes  and  the  motor  fields,  are  made  as  indicated  through  the 


METHODS    OF    CIRCUIT-CHANGING. 


487 


Fro.  361.— Diagram  Plan  of  the  Several  Parts  of  an  Electrical  Vehicle  Driving  Circuit. 
The  field-windings  and  armatures  are  shown  projected,  the  proper  wiring  connec- 
tions being  indicated.  The  periphery  of  the  controller  is  laid  out  within  the  broken 
line  rectangle,  the  contacts  and  connections  through  it  for  varying  the  circuits 
through  four  speeds  being  shown.  A,  B,  C,  D,  E,  F,  G  are  the  terminal  contact  points 
of  the  various  speed  circuits,  to  be  made  as  the  positions  of  the  controller  contacts 
are  varied.  A',  B',  C',  D',  E',  F'  are  the  controller  contacts,  which,  with  those 
already  mentioned,  make  the  proper  circuits  for  the  first  speed.  Similarly,  A2,  Ba, 
Ca,  etc.,  when  brought  into  contact  with  A,  B,  C.  etc.,  give  the  second  speed  circuits; 
B3,  C3,  E3,  F3,  in  contact  with  A,  B,  C,  D,  etc.,  give  the  third  speed;  and  B4,  C4,  D4, 
in  the  same  manner,  the  fourth  speed,  The  reverse  switch  gives  the  backward  move- 
ment, as  described, 


488 


SELF-PROPELLED    VEHICLES. 


rotary  reversing  switch,  by  the  terminals,  K,  L,  M,  N.  This 
switch  may  effect  the  reversal  of  the  motors  by  giving  a  quarter 
turn  to  its  spindle,  which  means  that  the  contacts  of  segment,  X, 
will  be  shifted  from  L  and  K  to  K  and  N,  and  the  contacts  of 
segment,  F,  shifted  from  M  and  N  to  L  and  M,  thus  reversing 
the  direction  of  the  current. 

Electric  Vehicle  Company's  Circuits. — Some  leading  manu 
facturers  of  electric  vehicles,  notably  the  Electric  Vehicle  Co., 


^-^m 


X-WJW\ 


FIG.  362 — Diagram  of  a  Typical  One-Battery-Unit,  Two-Motor  Circuit.  The  first  speed 
shows  the  two  motors  tn  series,  with  a  resistance  coil  interposed;  the  second,  the 
motors  in  series,  without  the  resistance;  the  third,  the  motors  in  multiple. 

vary  the  scheme  shown  in  the  last  two  figures  by  connecting  the 
armature  brushes  and  fields  of  each  motor  into  series,  and  shift- 
ing the  circuit  connections,  where  two  motors  are  used,  from 
series  to  series-parallel.  In  the  figure  showing  the  combination 
of  one  battery  unit  with  two  motors,  the  connections  for  the  three 
speeds  obtained  are  obvious.  Since  only  one  unit  is  used,  the 
lowest  pressure  of  the  battery  can  be  obtained  only  by  inserting 
a  resistance  coil,  R,  in  the  circuit,  with  the  armature  brushes, 


METHODS    OF    CIRCUIT-CHANGING. 


489 


field  windings  and  both  motors  connected  in  series.  For  the 
second  speed  the  resistance  is  simply  cut  out,  allowing  the  full 
voltage  of  the  battery  to  pass  through  the  armatures  and  wind- 
ings of  both  motors,  still  connected  in  series.  For  the  third 
speed  the  connections  of  armatures  and  motors  are  shifted  to 
multiple,  or  series-multiple.  With  the  use  of  a  two-unit  bat- 

/€.*  SPEED 


H 


**  SPEED 


HhlililiH 


"|i|i|iH|i|i|i|ik 


FIG.  363.— Diagram  of  a  Typical  Four-Battery-Unit,  Single-Motor  Circuit,  showing  combi- 
nations for  three  speeds.  The  only  changes  made  in  these  circuits  are  in  the  battery 
connections.  For  the  first  speed  the  battery  units  are  in  multiple;  for  the  second, 
in  series-multiple;  for  the  third,  in  series.  The  motor  connections  are  not  varied. 

tery  and  two  motors,  it  is  possible  to  eliminate  the  resistance 
coil  altogether  and  depend  entirely  upon  circuit  shifting  regulat- 
ing the  voltage  and  power.  Accordingly,  for  the  first  speed  we 
have  the  batteries  connected  in  multiple,  and  the  armatures  and 
windings  of  the  two  motors  in  series.  For  the  second  speed, 


490 


SELF-PROPELLED    VEHICLES. 


the  series  connections  are  adopted  for  both  batteries  and  motors, 
while  for  the  third  speed  the  batteries  are  in  series,  with  the 
motors  in  parallel. 

A  Four-Battery-Unit,  One-flotor  Circuit. — In  the  diagram  in- 
dicating the  use  of  four-battery-units  with  one  motor,  which,  as 
shown  in  an  accompanying  cut,  is  used  to  drive  both  rear  wheels 
of  the  wagon  through  a  single  reduction,  it  is  possible  to  obtain 


SPEED 


FIG.  364.—  Diagram  of  a  Two-Battery-Unit,  Two-Motor  Circuit,  showing  combinations  for 
three  speeds.  The  first  speed  is  obtained  with  the  battery  units  in  multiple,  and  the 
motors  in  series;  the  second,  with  the  battery  units  in  series,  and  the  motors  in 
series;  the  third,  with  the  battery  units  in  series,  and  the  motors  in  multiple. 

a  still  greater  range  of  variation  by  the  simple  shifting  of  the  bat- 
tery circuits,  without  alteration  of  the  armature  or  field  connec- 
tions. Accordingly,  for  the  first  speed  we  have  the  four  units 
connected  into  parallel,  which  gives  a  total  voltage  equivalent  to 
the  voltage  of  any  one  of  them.  For  the  second  speed,  the  bat- 
tery units  are  connected  into  series,  the  two  pairs  thus  formed 
being  joined  in  multiple,  with  the  result  that  the  total  voltage  of 
the  battery  is  equivalent  to  the  sum  of  the  voltage  of  two  of  the 


METHODS   OF   CIRCUIT   CHANGING. 


491 


units,  or  twice  the  voltage  used  in  the  first  speed.  For  the  third 
spee.d,  all  four  units  of  the  battery  are  connected  into  series,  thus 
doubling  the  voltage  again,  and  realizing  the  highest  speed  and 
power  efficiency  possible  in  the  combination. 

Vehicle  Circuit  Arrangements. — The  next  two  figures  illus- 
trate different  methods  of  arranging  the  circuits  of  an  electric 


Q g  Q-Q  [>Q-Q 

SEc<w*SP££J>[] []          Q-Q 


r/fOTO*i 

/i/W/*ru/i£ 


+  a 


I 


6~?)6~^ 


o 

-f1      SATreXY    TCKM4AIA16      ~" 


FIG.    365. — Diagram    of    Controller    Connections    of    a    One-unit,    One-motor 
Circuit,  with  Variable  Fields. 

vehicle  in  actual  practice.  In  the  first,  which  shows  the  arrange- 
ments used  on  light  Waverley  carriages,  the  one-unit  battery  in 
three  trays  is  shown  connected  in  an  invariable  series  circuit, 
giving  the  first,  or  lowest,  speed  through  the  resistance  coil  be- 
tween controller  contacts,  I  and  2,  the  motor-fields  being  in 
series ;  the  second  speed  with  the  same  circuit  without  the  re- 


492 


SELF-PROPELLED    VEHICLES. 


[ 

fll 

I 

] 

1 

Afa  d 


o  o  D 

DODO 

o  ; 

0   0 

Z'-'&p.tJ  ihead. 


0:.1.L.|-  Lvi-T  I 


^s/tetd  back 


FIG.  366.— Diagram  of  Controller  Connections  of  a  Four-unit,  One-motor, 
Circuit,  with  Constant  Series  Connections  for  Fields  and  Armature  in 
Forward  and  Backward  Speeds. 


METHODS  OF  CIRCUIT  CHANGING.  493 

sistance,  and  the  third  speed  with  the  motor-fields  in  parallel. 
The  motor  used  on  these  carriages  is  of  the  six-pole  type,  the 
field  coils  being  divided  into  two  halves  of  three  coils  each,  each 
half  being  independently  connected  to  the  controller  contacts,  as 
shown  in  the  cut.  Reversal  is  by  a  form  of  rotatable  switch, 
and  an  electric  brake  is  also  used,  which  operates  on  the  princi- 
ple of  reversing  the  polarity  between  the  armature  and  field 
windings.  In  the  second  diagram  is  shown  the  connections  of  a 
series  motor,  in  which  the  field  and  armature  windings  are  in 
invariable  series  connections  for  all  forward  speeds.  The  first, 
or  lowest,  speed  forward  is  obtained  with  three  units  of  the  bat- 


PIG.  367.— A  Typical  Electrical  Vehicle  Controller,  or  Circuit-changing 
Switch.  The  circuit  terminals  of  battery  and  motors  are  shown  at  the 
jack-springs,  which  are  arranged  to  be  engaged  by  the  fins  on  the  per- 
iphery of  the  controller-cylinder.  The  connections  within  the  controller, 
between  the  fins,  are  the  same  as  those  shown  in  Fig.  366,  except  for 
the  fact  that  the  four  rings  at  the  right  hand  end  provide  constant  volt- 
age connections  for  use  with  a  shunt  motor.  The  gaps  at  the  rear  of  the 
rings  show  means  for  cutting  out  the  shunt  field  at  top  speed. 

tery  in  series-multiple ;  the  second,  with  the  four  units  in  series- 
multiple ;  the  third,  with  the  four  units  in  series.  In  reversing, 
the  first  and  second  speeds  backward  correspond  to  the  for- 
ward speed  arrangements  similarly  numbered,  with  the  excep- 
tion that  the  connections  of  field  and  armature  are  reversed,  as 
may  be  readily  understood  from  following  out  the  indicated 
connections.  In  the  charging  position,  the  three  contacts  at  the 
right  side  of  the  controller  are  cut  out,  leaving  the  battery  to 
be  charged  in  series  from  the  charging  plug  connections  to  con- 
tact, A,  at  the  left  of  the  controller,  to  the  similar  connections 
with  the  negative  pole  of  battery,  4. 


494 


SELF-PROPELLED   VEHICLES. 


The  Controller  of  an  Electric  Vehicle. — The  controller  of 
an  electric  vehicle  consists  of  a  rotatable  insulated  cylinder,  car- 
rying on  its  circumference  a  number  of  contacts,  arranged  to 
make  the  desired  connections  with  the  terminals  of  the  various 
apparatus  in  the  circuit  through  a  wide  range  of  variation.  As 
shown  in  the  figure  of  the  arrangement  of  the  battery  and  con- 
trollers in  a  typical  electric  vehicle,  these  points  are  disposed 
so  that  the  units  of  the  battery  may  be  connected  in  series  or 
multiple,  and  that  the  field  windings  of  the  motors  may  be  simi- 
larly varied.  As  shown  in  the  diagram,  this  act  is  accomplished 
by  a  series  of  variations  of  electrical  connection  among  the  con- 
tact points  on  the  periphery  of  the  controller.  Thus  we  find  that 


FIG.  368.— Typical  Controller  of  the  General  Electric  Co.,  showing  means  for 
making  circuit  connections  through  conducting  segments  on  the  per- 
iphery of  the  controller-cylinder. 

for  the  first  speed,  in  which  the  batteries  are  connected  in  multi- 
ple, the  points,  A' ,  C' ,  are  in  electrical  connection,  as  indicated 
by  the  lines  between  them,  so  that  the  points,  A,  C,  connected  to 
the  like  poles  of  the  two  battery  units,  are  directly  connected, 
thus  bringing  the  two  units  into  multiple.  The  battery  circuit 
is  completed  by  the  electrical  connection  on  the  controller  be- 
tween the  points,  B'  and  D' ,  when  they  are  brought  into  contact 
with  the  points,  B  and  D,  which  connect  to  the  two  other  poles 
of  the  battery.  Furthermore,  the  points,  £'  and  F,  being  in 
electrical  connection  through  the  body  of  the  controller,  connect 
points,  E  and  F,  direct,  thus  throwing  the  field  windings  of  the 


METHODS  OF  CIRCUIT  CHANGING. 


495 


motors  into  series.  As  may  be  understood  from  the  last  two 
diagrams  of  vehicle  circuits,  the  contacts  may  be  arranged  to 
make  any  of  several  schemes  of  circuit  variation,  although,  as 
must  be  obvious  on  examination,  a  specially  arranged  controller 
is  necessary  for  each  separate  scheme. 

Construction  of  a  Controller. — The  accompanying  cuts  show 
the  general  appearance  and  construction  of  several  types  of  con- 
troller for  electrical  vehicles.  As  may  be  seen  in  the  first  cut, 


FIG.  369.— Chassis  of  a  Heavy   Wagon   of  the   Electric  Vehicle  Co.,   showing 
arrangement  of  controlling  apparatus. 

the  connections  of  the  terminals  of  the  batteries,  of  the  field 
windings,  and  other  elements  of  the  circuit,  are  made  at  the 
binding  posts  at  the  front  base  of  the  instrument.  From  each 
of  these  binding  posts,  which  are  electrically  insulated  from  one 
another,  jack-springs  rise  to  a  position  convenient  to  make  con- 
nections with  the  switch  blades  arranged  along  the  periphery  of 
the  controller  cylinder.  These  switch  blades,  as  may  be  seen, 
are  secured  to  the  controller  cylinder  by  screw  connections,  be- 


496  SELF-PROPELLED   VEHICLES. 

ing  arranged  singly,  or  several  of  them  together  on  one  plate. 
In  the  case  of  a  pair  of  blades,  shown  in  contact  with  the  spring 
at  either  extremity  of  the  controller  cylinder,  it  is  evident  that 
there  is  an  electrical  contact,  through  the  base  plates,  between 
the  two  terminals,  represented  by  the  contact  springs  in  engage- 
ment. Between  these  two  end  plates,  as  may  be  seen,  there 
are  several  switch  blades  arranged  singly  upon  the  circumfer- 
ence. At  one  point  there  is  no  contact  whatever,  showing  that 
the  terminals  represented  by  the  contact  springs  at  that  point  are 
out  of  circuit.  These  several  blades  that  are  arranged  singly  on 
the  controller  surface  have  such  electrical  connections  as  the 
scheme  of  circuit  variation  adopted  demands,  made  through  in- 
sulated wire  connections  arranged  between  any  pair  it  is  desired 
to  connect.  This  is  the  arrangement  indicated  in  the  diagram 
of  connections  already  described.  It  is  perfectly  easy  to  under- 
stand, therefore,  how  the  circuit  arrangements  of  battery  units 
and  motor  windings  may  be  varied  through  any  desired  range 
of  connections,  by  simply  connecting  their  terminals  through 
properly  arranged  and  connected  controller  contacts. 

Varieties  of  Controller. — The  controller  shown  in  the  cut, 
already  described,  represents  only  one  type  of  this  machine. 
Some  controllers  are  constructed  simple,  with  a  perfectly  cylin- 
drical surface,  upon  which  bear  single  leaf  springs,  the  desired 
electrical  connections  being  made  by  suitably  connected  conduct- 
ing surfaces  on  the  cylinder  circumference,  and  cut-outs  being 
similarly  accomplished  by  insulating  surfaces,  bearing  against 
the  spring  contacts  at  the  desired  points.  This  type  of  control- 
ler is  shown  in  the  second  cut,  and  is  one  of  the  most  usual 
forms  for  motor  vehicle  purposes.  As  is  perfectly  obvious,  it  is 
possible  to  so  arrange  the  electrical  connections  on  the  controller 
surfaces,  that  by  proper  contacts  with  the  terminal  springs,  re- 
versal of  the  motor  may  be  accomplished,  as  shown  on  the  last 
circuit  diagram.  This  is  done  in  a  number  of  controllers,  the 
reverse  being  accomplished  at  a  definite  notch  on  the  quadrant 
of  the  shifting  lever. 


CHAPTER    THIRTY-ONE. 

THE    CONSTRUCTION    AND    OPERATION    OF    STORAGE    BATTERIES. 

Storage  Cells  Not  Condensers. — As  already  stated,  electric 
vehicles  derive  their  power  from  storage  batteries,  which  are 
charged  from  a  suitable  charging  plant,  supplying  current  either 
from  the  street  power  lines,  or  from  the  dynamo  operated  by  any 
convenient  source  of  power.  The  word,  storage  battery,  as  ap- 
plied to  electrical  accumulators,  or  secondary  batteries,  is  some- 
what of  a  misnomer,  since  these  devices  are  in  no  sense  recep- 
tacles for  electrical  energy,  and  act  on  an  entirely  defferent  prin- 
ciple from  the  instrument  known  as  a  condenser,  which  depends 
solely  upon  such  variations  of  the  electrical  potential  between 
two  surfaces,  that  one  of  them  may  be  so  affected  by  the  electrical 
current,  momentary  or  prolonged,  as  to  give  forth  electrical  en- 
ergy in  the  form  of  a  shock,  when  brought  into  contact  with  any 
other  surface  having  a  low  or  negative  potential.  Such  a  device 
as  this  is,  of  course,  useless  for  any  purpose  requiring  a  constant 
current  between  two  points  of  different  potential,  such  as  is  re- 
quired for  any  kind  of  power  transmission. 

Cells,  Primary  and  Secondary. — The  so-called  electrical  ac- 
cumulator, or  storage  battery,  more  properly  to  be  described  as  a 
secondary  battery,  operates  on  an  entirely  different  principle, 
to  be  briefly  described  as  an  electro-chemical,  by  which  a  direct 
electric  current,  steadily  flowing  through  a  given  period,  can  pro- 
duce certain  chemical  changes,  which,  as  the  expression  is, 
"charge"  the  battery.  This  process  may  be  briefly  illustrated  by 
making  a  comparison  with  a  primary  galvanic  cell.  In  such  cells 
two  electrodes  of  dissimilar  substances,  such  as  copper  and  zinc, 
or  carbon  and  zinc,  are  immersed  in  a  liquid  solution,  in  the  first 
case  of  dilute  sulphuric  acid,  in  the  second  of  sal  ammoniac — al- 
though different  solutions  are  used  in  the  various  makes  of  cells. 
As  soon  as  the  two  electrodes,  thus  immersed  in  the  liquid,  are 
connected  by  a  wire  outside  of  the  solution,  so  as  to  form  a  com- 
plete circuit  between  them  through  the  liquid  and  back  again 
through  the  outside  wire,  an  electrical  current,  which  is  to  say, 

497 


498  SHIP-PROPELLED   VEHICLES. 

a  continuous  transmission  of  electrical  energy,  is  set  up.  This 
phenomenon  takes  place  in  accord  with  what  may  be  called  the 
specific  potential  of  the  two  metals.  This  means  that  if  two  such 
substances,  copper  and  zinc,  or  carbon  and  zinc,  be  brought  into 
contact  in  the  air,  there  will  be  a  distinct  impartation  of  energy 
from  the  former  to  the  latter  in  each  case,  showing  that  carbon 
and  copper  receive  and  give  off  a  charge  much  more  readily  than 
zinc.  On  the  other  hand,  when  two  such  substances  are  im- 
mersed in  the  electrolytic  solution  the  conditions  are  completely 
reversed,  the  impartation  of  energy  through  the  liquid  being 
from  the  zinc  to  the  copper  or  carbon.  Thus,  the  typical  gal- 
vanic cell  is  really  a  combination  of  the  phenomena  taking  place 
both  in  air — on  the  outside  wire,  between  the  portions  of  the  two 
plates  not  wet  with  solution — and  through  the  electrolyte.  This 
renders  the  galvanic  circuit  possible.  It  also  explains  the  fact 
that  the  zinc,  or  positive  plate  in  the  solution,  is  the  negative  ter- 
minal of  the  outside  wire. 

The  Operation  of  a  Galvanic  Cell. — In  an  assembled  galvanic 
cell  of  any  type  the  operations  taking  place  before  the  circuit  of 
the  outside  wire  is  closed  are  purely  chemical;  only  when 'the 
circuit  is  closed  does  electrical  energy  begin  to  manifest  itself 
in  the  form  of  current.  The  same  chemical  processes  then  con- 
tinue, with  the  result,  however,  iof  doing  useful  work.  The  first 
result  of  closing  the  circuit  is  the  decomposition  of  the  electro- 
lyte into  its  component  parts.  If  it  is  dilute  sulphuric  acid 
(H2  SO4),  the  decomposition  is  into  hydrogen,  oxygen  and  sul- 
phuric oxide — the  oxygen  uniting  with  the  zinc  and  gradually 
consuming  it,  and  the  hydrogen  being  collected  on  the  face  of  the 
copper  plate  in  the  form  of  minute  bubbles.  In  practical  cells 
it  is  necessary  to  use  some  substance,  known  as  the  "depolarizer," 
that  has  a  high  affinity  for  hydrogen,  in  order  that  the  hydrogen 
may  be  constantly  absorbed  and  the  process  allowed  to  continue 
until  the  zinc  is  exhausted.  Were  it  possible  to  "restore"  a 
primary  chemical  cell,  so  that  the  zinc  oxide  would  again  be- 
come metallic  zinc,  and  the  electrolyte  be  re-composed  from  its 
elements,  we  would  have  a  very  fair  duplication  of  the  conditions 
theoretically  found  in  a  secondary,  or  storage,  cell — except  for 
the  fact  that  in  the  latter  the  processes  taking  place  on  the  out- 
side wire  are  the  same  as  those  occurring  in  the  electrolyte  in  the 


STORAGE  BATTERIES.  499 

primary,  and  vice  versa.  This  means  that  the  hydrogen  collects 
on  the  plate  connected  to  the  negative  lead,  while  the  destructive 
chemical  changes  occur  in  that  connected  to  the  positive  lead  of 
the  outside  circuit 

The  General  Theory  of  Storage  Batteries. — The  general 
theory  upon  which  a  secondary  battery  operates  was  discovered  as 
early  as  1801,  when  Gautherot  discovered  that  if  two  plates  of 
platinum  or  silver,  immersed  in  a  suitable  electrolyte,  are  con- 
nected to  the  terminals  of  an  active  primary  cell  and  current  is 
allowed  to  flow  for  any  desired  period,  a  small  current  could  be 
obtained  on  an  outside  circuit  connecting  these  two  electrodes, 
as  soon  as  the  primary  battery  had  been  disconnected.  The  pro- 
cess which  takes  place  in  this  case  is  briefly  as  follows :  An  elec- 
trolyte, consisting  of  a  weak  solution  of  sulphuric  acid,  permits 
ready  conduction  of  the  current  from  the  primary  battery,  the 
greater  the  proportion  of  acid  in  certain  limits  the  smaller  being 
the  resistance  offered.  The  effect  of  the  current  passing  through 
the  electrolyte  is  the  decomposition  of  the  water,  which  is  indi- 
cated by  the  formation  of  bubbles  upon  the  exposed  surfaces  of 
both  electrode  sheets,  these  bubbles  being  formed  by  oxygen  gas 
on  the  plate  connected  to  the  positive  pole  of  the  primary  battery, 
and  hydrogen  on  the  plate  connected  to  the  negative  pole  of  the 
battery.  Because,  however,  the  oxygen  is  unable  to  attack  either 
platinum  or  silver  under  such  conditions,  the  capacity  of  such  a 
device  to  act  as  an  electrical  accumulator  is  practically  limited 
to  the  point  at  which  both  plates  are  covered  with  bubbles.  After 
this  point  the  gases  will  begin  to  escape  into  the  atmosphere.  In 
this  simple  apparatus,  as  in  the  storage  cells  manufactured  at  the 
present  day,  the  prime  condition  to  operation,  is  that  the  resist- 
ance of  the  electrolyte  should  be  as  low  as  possible,  in.  order  that 
.the  current  may  pass  freely  and  with  full  effect  between  the  elec- 
trodes. If  the  resistance  of  the  electrolyte  is  too  small,  the  cur- 
rent intensity  will  cause  the  water  to  boil  rather  than  to  occasion 
the  electrolytic  effects  noted  above. 

As  soon  as  the  current  from  the  primary  cell  is  discontinued, 
and  the  two  electrode  plates  from  the  secondary  cell  are  joined 
by  an  outside  wire,  a  small  current  will  be  caused  to  flow  upon 
that  outside  circuit  by  the  recomposition  of  the  acid  and  water 
solution.  The  process  is  in  a  very  definite  sense  a  reversal  of 


500  SELF-PROPELLED    VEHICLES. 

that  by  which  the  current  is  generated  in  a  primary  cell.  Hydro- 
gen collected  upon  the  negative  plate,  which  was  the  cathode,  so 
long  as  the  primary  battery  was  in  circuit,  is  given  off  to  the 
liquid  immediately  surrounding  it,  uniting  with  its  particles  of 
oxygen  and  causing  the  hydrogen,  in  combination  with  them,  to 
unite  with  the  particles  of  oxygen  next  adjacent,  continuing  the 
process  until  the  opposite  positive  plate  is  reached,  when  the 
oxygen  collected  there  is  finally  combined  with  the  surplus  hydro- 
gen, going  to  it  from  the  surrounding  solution.  This  chemical 
process  causes  the  current  to  emerge  from  the  positive  plate, 
which  was  the  anode,  so  long  as  the  primary  battery  was  in  cir- 
cuit. The  current  thus  produced  will  continue  until  the  recom- 
position  of  the  gases  is  complete ;  then  ceasing  because  these 
gases,  as  before  stated,  do  not  combine  with  the  metal  of  the 
electrodes. 

Requirements  in  a  Practical  Storage  Battery. — In  order  to 
produce  a  secondary  battery  that  shall  be  able  to  give  forth  a  cur- 
rent of  sufficient  strength  and  duration  for  practical  purposes, 
it  is  necessary  to  employ  some  metal  that  can  be  attacked  by  the 
oxygen  produced  in  the  process  of  "charging,''  but  which  at  the 
same  time  is  capable  of  being  restored  to  its  normal  condition 
when  the  operation  is  reversed  and  current  is  taken  off  from  the 
cell.  Hitherto,  the  substance  found  most  suitable  for  this  pur- 
pose has  been  lead,  which,  until  the  perfection  of  Edison's  iron- 
nickel  cell,  has  been  in  practically  universal  use  for  the  plates 
and  grids  of  storage  batteries.  Of  course,  under  operative  con- 
ditions, the  restoration  of  the  metal  is  not  perfect ;  also,  continual 
chargings  and  dischargings  inevitably  result  in  the  breaking- 
down  of  the  plates,  involving  that  they  be  replaced. 

The  Plante  Secondary  Cells. — About  1860  Gaston  Plante,  a 
French  electrician,  perfected  the  first  practical  storage  cell  con- 
structed by  folding  together  spirally  two  sheets  of  metallic  lead, 
separated  by  a  thin  septum  of  canvas  or  a  strip  of  gutta  percha 
and  immersed  in  a  weak  solution  of  sulphuric  acid.  When  a 
current  from  a  primary  battery  is  passed  through  the  electrolyte 
between  the  two  lead  sheets,  the  same  process  takes  place  as 
was  described  in  connection,  with  Gautherot's  primitive  platinum 
cell.  Oxygen  and  hydrogen,  liberated  by  electrolysis,  Collect  upon 


STORAGE   BATTERIES. 


501 


the  surface  of  the  plates,  thus  forming  the  electro-chemical  basis 
for  the  production  of  a  current,  so  soon  as  the  primary  electrical 
source  is  disconnected.  The  operation  differs,  however,  from 
that  formerly  noted,  in  the  fact  that  oxygen  bubbles  do  not  ap- 
pear upon  the  surface  of  the  anode,  but  effect  a  chemical  change 


FIG.  370.—  A  Typical  Storage  Cell  Enclosed  in  a  Glass  Jar.  This  cell  repre- 
sents one  of  the  best-known  makes  of  the  Plante  genus.  With  five 
plates,  as  shown,  such  a  cell  has  a  capacity  of  80  ampere-hours,  at  8 
hours'  discharge;  of  70  ampere-hours,  at  5  hours'  discharge;  of  60  am- 
pere-hours, at  3  hours'  discharge,  with  a  discharge  rate  of  10  amperes 
in  8  hours;  of  14  amperes  in  5  hours,  and  of  20  amperes  in  3  hours.  The 
total  outside  dimensions  of  this  cell  are  5^x9^x11  y4  inches;  dimensions 
of  each  plate's  active  surface,  7^x7f4  inches. 


in  the  plate.  The  oxygen  attacks  the  lead,  forming  lead  peroxide. 
By  disconnecting  the  primary  source  a  weak  current  can  be  pro- 
duced from  this  cell,  until  the  normal  conditions  have  been  re- 
stored, as  previously  explained  ;  but,  in  order  to  fit  it  for  any  kind 
of  practical  use,  it  must  be  suitably  "formed,"  which  process 


502  SELF-PROPELLED    VEHICLES. 

originally  consisted  in  applying  a  charging  current,  first  in  one 
direction,  then  in  the  other,  and  allowing  a  discharge  to  follow  in 
each  case.  In  this  process,  which  should  occupy  about  two 
months,  the  following  series  of  changes  take  place:  The  lead 
peroxide  collected  on  the  surfaces  of  one  of  the  sheets,  gradually 
disappears,  as  directed  by  the  change  in  the  color  from  brown 
to  lead  metallic.  The  peroxide,  however,  gradually  begins  col- 
lecting on  the  surface  of  the  other  plate,  and  so  continues  so  long 
as  the  current  endures.  A  plate  from  which  the  peroxide  has 
been  separated,  by  repeated  alternations  of  the  charging  current, 
assumes  a  spongy  character,  which  enables  the  augmentation  of 
its  electrical  accumulating  property  by  increasing  the  surface 
exposed  to  the  attacks  of  the  oxygen  gas.  This  process  of  "form- 
ing" by  repeated  alternations  of  the  charging  current,  produced 
a  high  standard  of  efficiency ;  the  average  power  output  of  the 
earlier  types  of  the  Plante  cell  having  been  7^4  ampere-hours  per 
pound  of  lead,  which  is  as  good  as  has  since  been  achieved.  How- 
ever, it  rendered  the  plates  very  nearly  rotten  by  the  time  the 
maximum  capacity  had  been  achieved.  As  a  consequence  the 
later  types  of  this  variety  of  cell  -are  composed  of  plates  formed 
by  pickling  baths  of  50  per  cent,  solution  of  nitric  acid.  After  an 
immersion  of  from  24  to  48  hours  in  this  solution,  they  are 
treated  with  a  10  per  cent,  solution  of  sulphuric  acid,  or  by  a 
thorough  washing  in  ammonia,  followed  by  heating  in  a  furnace 
to  a  temperature  of  203  degrees  Centigrade.  Other  processes, 
generally  of  a  secret  nature,  are  also  used  to  further  prepare  the 
plates.  After  this  they  are  in  a  condition  to  be  used  in  a  prac- 
tical secondary  battery,  the  process  and  conditions  of  charging 
being  essentially  the  same,  as  have  already  been  described. 

A  typical  American  storage  cell  of  the  Plante  genus  is  shown 
in  the  several  accompanying  illustrations,  which  serve  to  show 
the  essential  features  of  this  variety  of  accumulator.  Both  the 
positive  and  negative  plates  are  constructed  with  a  large  number 
of  deep  parallel  grooves,  cut  by  means  of  a  special  tool.  This 
process  is  termed  "spinning."  In  order  to  "form"  the  battery 
the  plates,  thus  suitably  grooved,  are  placed  in  a  strong  oxidizing 
solution,  generally  ammonia  nitrate,  after  which  the  current  is 
passed  through  the  solution  transforming  the  oxides  into  per- 
oxides. This  treatment  is  continued  until  the  entire  space  be- 
tween the  leaves  is  filled  with  active  material.  The  formed  plates 


STORAGE   BATTERIES. 


503 


are  reformed  as  negatives  to  cast  off  nitrates,  then  washed  as  a 
further  protection  against  nitrates.  Plates  intended  for  positives 
are  reformed  in  a  sulphuric  acid  electrolyte.  After  these  pro- 
cesses, the  positive  and  negative  plates  may  be  assembled  into 
cells,  the  necks  being  burned  on,  so  as  to  connect  each  one  to  its 
respective  terminal,  the  cells  formed  by  a  number  of  these  plates 
— an  odd  number  of  positives  and  an  even  number  of  negatives — 
have  sheets  of  porous  hard  rubber  between  each  pair  of  plates. 

With    batteries    of   this    make,    intended    for    use    in    electric 
vehicles,  a  voltage  output  of  from  eight  to  ten  watts  per  pound 


FIG.  371.— One  Plate,  or  "Grid,"  of  a  Type  of  Storage  Cell  constructed  by 
inserting  buttons  or  ribbons  of  the  proper  chemical  substances  in  perfo- 
rations. Some  such  cells  use  crimped  ribbons  of  metallic  lead  for  in- 
serting in  the  perforations,  others  pure  red  lead  or  other  suitable 
material 

of  total  battery  weight  may  be  realized.  The  duration  of  its 
period  of  usefulness  is  also  considerably  longer  than  that  realized 
in  many  other  types  of  cell,  which  is  a  quality  claimed  for  several 
of  the  most  representative  batteries  of  the  Plante  genus. 

The  Faure  Secondary  Cells. — The  Faure  cells,  first  invented 
in  1 88 1,  differ  from  the  original  Plante  variety  in  the  fact  that  the 
process  of  forming  is  largely  done  away  by  "pasting,"  or  apply- 
ing active  material  directly  to  the  surfaces  of  the  plates,  or 
"grids,"  in  pockets  or  perforations.  This  involves  that  the  lead 


504  SBLP-PROPELLED   VEHICLES. 

grids  be  specially  prepared  for  the  purpose,  and  designs  in  large 
variety,  intended  to  increase  the  active  surface,  while  maintain- 
ing the  strength  of  the  structure,  have  been  used  by  as  many  dif- 
ferent inventors  and  manufacturers.  One  trouble  with  many 
such  pasted  cells  has  been  that  the  grids  are  heavy  in  proportion 
to  the  amount  of  active  surface  exposed,  and,  that  they  are  liable 
to  warp  or  buckle,  allowing  portions  of  the  active  substance  to 
fall  between  adjacent  plates,  short-circuiting  the  cell.  The  sub- 
stances most  often,  used  in  the  Faure  type  of  cell  are  minium  or 
red  lead  oxide  (Pb3  O4)  and  lead  monozide  or  litharge  (Pb  O). 
The  former  under  the  action  of  the  electrolyte  becomes  the  so- 
called  "red  lead  salt,"  the  latter,  the  "buff  lead  salt."  Some  cells 
using  grids  with  perforations  for  holding  the  active  material  are 
made  somewhat  differently.  Thus,  as  stated  by  several  authori- 
ties, in  a  type  of  cell  widely  used  in  America  the  positive  plates 
or  "grids''  are  composed  of  an  alloy  of  lead  and  antimony,  cast 
into  shape  with  a  certain  number  of  round  perforations.  Each  of 
these  holes  is  then  filled  with  a  button,  made  by  rolling  a  crimped 
lead  ribbon  into  a  coil  of  proper  size  to  fit  it  tightly.  By  an  elec- 
tro-chemical process,  the  required  lead  oxide  is  then  produced. 
The  negative  grids  are  made  of  casting  the  proper  shape,  under 
heavy  pressure,  around  a  number  of  square  blocks  of  fused 
chloride  of  zinc  and  chloride  of  lead.  When  the  grid  is  com- 
pleted, the  zinc  is  chemically  removed,  leaving  the  contents  of 
each  perforation  pure  spongy  lead.  The  plates  are  now  ready  to 
be  assembled  into  a  cell  and  to  begin  work  as  soon  as  the  cur- 
rent has  passed  through  the  electrolyte  composed  of  a  solution 
of  sulphuric  acid.  Cells  specially  adapted  for  automobile  work 
are  produced  by  the  same  manufacturers. 

The  series  of  operations  taking  place  during  the  charge  or 
discharge  of  a  storage  cell  are  very  complicated,  and  need  not 
be  fully  discussed  at  the  present  time.  It  is  desirable,  however, 
to  outline  them  in  a  general  way.  In  discharging  a  cell  the 
oxygen  in  the  electrolyte  attacks  the  spongy  surface  of  each  nega- 
tive plate,  releasing  hydrogen,  which,  in  turn,  reduces  the  lead 
peroxide  or  dioxide  (PbO0)  of  each  positive  plate  to  monoxide 
(Pb  O).  The  surplus  radical  of  the  acid  then  combines  with  the 
active  material  on  both  plates,  producing  sulphates  and  thus  re- 
ducing the  specific  gravity  of  the  electrolyte.  Although  this  "sul- 
phating"  of  the  plates  is  a  common  and  necessary  part  of  the 


STORAGE   BATTERIES.  505 

process  of  discharge,  it  is  a  source  of  trouble,  if  allowed  to  be- 
come excessive,  as  in  an  overdischarge— below  1.8  or  1.75  volts. 
In  charging,  the  current  passes  from  the  each  positive  plate 
through  the  electrolyte  to  the  negative,  exerting  the  effect  of 
decomposing  the  sulphate  and  transferring  all  the  oxygen  from 
the  negative  to  the  positive  plates.  The  negative  plates  are  thus 
freed  from  oxide,  becoming  merely  spongy  or  porous  metallic 
lead;  while  the  positive  plates  contain  no  oxides  lower  than  the 
peroxide,  with  the  probable  addition  of  some  sulphates.  Owing 
to  the  decomposition  of  the  sulphates,  the  specific  gravity  of  the 
electrolyte  is  at  its  highest  on  completion  of  the  charge.  The 
limit  of  charging  capacity  is  carefully  determined  for  each  type 
of  cell,  but  may  be  readily  recognized  by  the  giving-off  of  oxygen 
and  hydrogen  gases.  The  condition  of  the  plates  may  also  be 
known  by  their  color.  Thus,  at  full  charge  the  positives  are 
dark  brown  and  the  negatives,  dark  slate  colored ;  at  discharge 
the  positives  are  chocolate  brown  and  the  .negatives,  light  slate 
colored.  The  specific  gravity  of  the  electrolyte  also  gives  an 
indication  on  this  point,  as  above  suggested.  Sulphating  and 
over-discharge  are  indicated  by  a  drab  color  of  the  positive  plates. 

Considering  only  the  reactions  that  affect  the  active  materials, 
we  have  the  following  formulae,  as  given  by  several  authorities : 

In  charging 

POSITIVE:  PLATES. 
PbS04+S04+2H20=Pb02+2H2S04. 

NEGATIVE    PLATES. 

PbS04+2H=Pb+H2S04. 

In  discharging 

POSITIVE  PLATES. 

(i)    Pb02+2H=PbO+H20. 

(2)    PbO+H2S04=PbS04+H20. 

NEGATIVE  PLATES. 

Pb+H2SO4=PbSO4+2H. 

Combining  these  equations,  we  have  the  "practical  universal 
equation,"  as  given  by  several  authorities : 

Pb02+2H3S04+Pb=:2H20+2PbS04. 


506  SELF-PROPELLED   VEHICLES. 

This  means  simply  that  a  combination  of  lead  peroxide  (i  part), 
metallic  lead  (i  part),  sulphuric  acid  (2  parts),  gives,  in  process 
of  discharge,  water  (2  parts)  and  lead  sulphate  (2  parts) — the 
process  being  reversed  during  charging. 

For  a  cell  previously  charged,  and  using  red  lead  salt  as  the 
active  material,  the  following  series  of  changes  are  given  by 
Frankland  and  quoted  by  other  authorities : 

In  charging 

POSITIVE:  PLATES. 
S2Pb8010+02+20H2=3Pb02+2S04H2. 

NEGATIVE  PLATES. 
S2Pb3010+4H2=3Pb+2S04H2+2OH,J. 

In  discharging 

POSITIVE  PLATES. 

3Pb02+2S04H2+2H2=S2Pb3010+4OH2. 

NEGATIVE  PLATES. 

3Pb+2S04H2+202=S2Pb3010+2H2. 

Points  on  Care  and  Operation. — On.  the  manner  of  operating 
and  maintaining  storage  batteries  for  use  in  electric  vehicles  and 
for  other  purposes,  there  are  a  number  of  points  to  be  considered. 

However,  since  full  directions  are  always  furnished  by  manu- 
facturers with  each  set  of  cells,  it  is  necessary  to  give  only  the 
merest  outlines  here.  Nearly  the  most  important  matter  for  the 
beginner  to  understand  thoroughly  is  that  relating  to  the  prepar- 
ation and  use  of  the  electrolyte.  As  has  been  already  stated,  this 
consists  of  i  part  of  chemically  pure  concentrated  sulphuric  acid 
mixed  with  several  parts  of  water.  The  proportion  of  water 
differs  with  the  several  types  of  cell  from  3  parts  to  8  parts,  as 
specified  in  the  directions  accompanying  the  cells.  In  making  the 
mixture  it  is  necessary  to  use  an  hydrometer  to  test  the  specific 
gravity  of  both  the  acid  and  the  solution.  The  most  suitable  acid 
should  show  a  specific  gravity  of  about  1.760,  or  66°  Baume. 

The  mixture  should  be  made  by  pouring  the  acid  slowly  into 
the  water,  never  the  reverse.  As  cannot  be  too  strongly  stated, 


STORAGE   BATTERIES. 


50T 


it  is  very  dangerous  to  pour  the  water  into  the  acid,  and  too  much 
care  cannot  be  exercised  on  this  point.  The  reason  is  that  great 
heat  is  generated  when  the  water  and  acid  come  into  contact, 
and  an  explosion  is  more  than  likely  to  be  the  result.  Since 
concentrated  sulphuric  acid — popularly  known  as  oil  of  vitriol — 
is  immensely  corrosive,  it  will  burn  the  flesh  painfully,  disfigure 
the  face  and  destroy  the  eyes.  Therefore,  a  person  unskilled  in 
chemistry  should  handle  it  with  the  greatest  care,  and  only  in  ac- 


FIG.  372.— "Unformed"  Plate  of  One  Pattern  of  "Gould"  Storage  Cell.  The 
particular  plate  shown  has  total  outside  dimensions  of  6x6  inches. 
The  clear  outline  of  the  grooves  indicates  absence  of  oxides,  due  to 
action  of  "forming"  solutions,  or  charging  current. 


cordance  ivith  directions.  Care  should  always  be  taken  that  the 
water  used  is  pure  as  possible,  distilled  water  or  rain  water  being 
preferable.  River  and  well  water  should  never  be  used  for  this 
purpose,  since  it  contains  certain  salts  of  chlorine  and  ammonia, 
which  are  apt  to  seriously  affect  the  plates  and  shorten  the  life  of 
the  battery. 

When  made  the  solution  should  be  allowed  to  cool  for  several 
hours    or    until    its    temperature    is    approximately    that    of 


508  SELF-PROPELLED    VEHICLES. 

the  atmosphere  (60°  being  the  average).  At  this  point 
it  should  have  a  specific  gravity  of  about  1,200  or  25° 
Baume.  If  the  hydrometer  shows  a  higher  reading  distilled 
water  may  be  added  until  the  correct  reading  is  obtained ;  if  a 
lower  reading,  dilute  acid  may  be  added  with  similar  intent. 

The  electrolyte  should  never  be  mixed  in  jars  containing  the 
battery  plates,  but  preferably  in  stone  crocks,  specially  prepared 
for  the  purpose.  Furthermore,  it  should  never  be  placed  in  the 
cell  until  perfectly  cool. 

As  soon  as  possible  after  placing  the  electrolyte  in  the  cell,  the 
charging  current  should  be  applied.  In  other  words,  the  elec- 
trolyte should  not  be  placed  in  a  new  cell  until  it  is  time  to  charge 
it.  If  this  is  not  done,  the  acid  solution  will  act  upon  the  plates, 
producing  sulphates  of  lead,  and  with  pasted  cells  virtually  in- 
sulating the  active  material  from  the  metal  of  the  grids,  which  is 
an  extremely  difficult  condition  to  remedy. 

For  precisely  similar  reasons,  a  battery  should  be  maintained 
at  as  near  full  charge  as  possible,  particularly  when  used  irregu- 
larly and  allowed  to  stand  idle  for  periods  between  times  of  oper- 
ation. After  a  long  run,  when  almost  exhausted,  recharging 
should  be  begun  as  soon  as  possible.  A  battery  should  never  be 
allowed  to  "rest,"  unless  it  is  disassembled  and  its  elements 
are  dried  and  treated  according  to  directions  furnished  by  the 
makers.  By  observing  these  rules  caiefully,  the  life  of  the  ap- 
paratus may  be  lengthened  and  its  usefulness  unimpaired  by 
sulphating  and  other  causes  of  imperfect  operation. 

Short=Circuiting. — A  form  of  derangement  that  may  occa- 
sionally affect  the  vehicle  batteries  is  short-circuiting.  It  may 
be  caused  by  some  of  the  active  material — if  the  cell  is  of  the 
pasted  variety — scaling  off  and  dropping  between,  the  plates,  or 
by  an  over-collection  of  sediment  in  the  bottom  of  the  cell.  If  by 
any  means,  also,  a  solid  conducting  foreign  substance  should  fall 
between  the  plates  when  the  cell  is  opened,  that  is  sufficient  to 
cause  the  difficulty.  Should  the  operator  suspect  trouble  with  his 
battery,  he  may  discover  a  short-circuited  cell  by  the  marked  dif- 
ference in  color  of  the  plates  or  of  the  specific  gravity  of  the  elec- 
trolyte, as  compared  with  the  other  cells.  No  particular  damage 
will  be  caused,  if  the  trouble  is  discovered  and  removed  before 
these  symptoms  become  too  marked.  If  a  foreign  substance  has 


STORAGE    BATTERIES. 


509 


510  SELF-PROPELLED    VEHICLES. 

become  lodged  between  the  plates,  it  may  be  removed  by  a  wood 
or  glass  instrument.  If  some  of  the  active  material  has  scaled  off, 
it  may  be  forced  dow,n  to  the  bottom  of  the  jar.  If  excessive  sedi- 
ment is  found,  the  jar  and  plates  should  be  washed  carefully,  and 
reassembled.  A  cell  that  has  been  short-circuited  may  be  discon- 
nected from  the  battery  and  charged  and  discharged  several  times 
separately.  This  may  remedy  the  trouble. 

In  placing  the  electrolyte  in  jars  containing  the  cells,  special 
care  should  be  taken,  that  the  entire  active  surface  of  the  grids  is 
completely  submerged.  They  should  always  be  at  least  one-half 
inch  below  the  surface  of  the  solution.  Whenever  it  is  necessary 
to  renew  the  electrolyte  this  rule  should  be  observed,  and  so  long 
as  the  batteries  are  in  operation  the  level  should  never  be  al- 
lowed to  fall  below  the  points  specified. 

Connections  for  Charging. — In  charging  a  storage  battery,  it 
is  of  prime  importance  that  the  connections  with  the  generator  be 
properly  arranged. .  This  means  that  the  positive  pole  of  the  gen- 
erator should  be  invariably  connected  to  the  positive  pole  of  the 
secondary  battery — which  is  to  say,  the  pole  which  is  positive  in 
action  when  the  current  is  emerging  from  the  secondary  battery, 
or  the  pole  that  is  connected  to  the  positive  plates.  As  this  is 
a  matter  of  prime  importance,  the  exact  polarity  of  both  gener- 
ator and  secondary  battery  terminals  should  be  accurately  de- 
termined before  attempt  is  made  to  charge.  An  error  in  this 
particular  will  result  in  entire  derangement  of  the  battery  and 
its  ultimate  destruction.  I,n  charging  a  storage  battery  for  the 
first  time  it  is  essential  that  the  current  should  be  allowed  to  enter 
at  the  anode  or  positive  pole  at  about  one-half  the  usual  charging 
rate  prescribed ;  but  after  making  sure  that  all  necessary  condi- 
tions have  been  fulfilled,  it  is  possible  to  raise  the  rate  to  that  pre- 
scribed by  the  manufacturers  of  the  particular  battery. 

Period  of  Charging  a  New  Battery. — With  several  of  the 
best  known  makes  of  the  American  storage  battery  the  prescribed 
period  for  the  first  charge  varies  between  twenty  and  thirty  hours. 
The  manufacturers  of  a  well-known  cell  of  the  Plante  genus  pre- 
scribe for  the  first  charge  half  rate  for  four  hours,  after  which 
the  current  may  be  increased  to  the  normal  power  and  continued 
for  twentv  hours  successively. 


STORAGE  BATTHRIHS.  511 

The  strength  of  current  to  be  used  in  charging  a  cell  should 
be  in  proportion  to  its  own  ampere-hour  capacity.  Thus,  as  given 
by  several  manufacturers  and  other  authorities,  the  normal  charg- 
ing rate  for  a  cell  of  400  ampere  hours  should  be  fifty  amperes; 
or  one-eighth  of  its  ampere-hour  rating  in  amperes  of  charging 
current  Before  closing  the  charging  circuit  it  is  essential  that 
the  voltage  of  the  generator  should  be  at  least  ten  per  cent,  higher 


FIG.  375.— One  Cell  of  the  "Gould"  Storage  Battery  for  Electric  Vehicle  Use. 
According  to  the  data  given  by  the  manufacturers,  this  cell,  containing 
four  negatives  and  three  positive  plates,  has  a  normal  charging  rate  of 
27  amperes;  a  distance  rate  of  22l/2  amperes  for  4  hours;  a  capacity  of 
81  ampere-hours  at  3  hours'  discharge,  and  of  90  ampere-hours  at  4 
hours'  discharge.  The  plates  are  each  5%x7^4  inches,  and  the  total  di- 
mensions of  the  cell,  enclosed  in  its  rubber  jar,  are  2^x6^4x11  inches. 
Forty  such  cells  are  generally  used  for  an  average  light  vehicle  battery. 

than  the  normal  voltage  of  the  battery  when  charged.  The  fact 
that  a  storage  cell  is  fully  charged  is  evident  by  the  apparent  boil- 
ing of  the  electrolyte  and  a  free  giving-off  of  gas.  It  may  also 
be  determined  by  the  voltmeter,  which  will  show  whether  the 
normal  pressure  has  been  attained.  At  the  first  charge  of  the 
battery,  the  voltage  should  be  allowed  to  rise  somewhat  above 
the  point  of  normal  pressure,  but  thereafter  should  be  discon- 


512  SELF-PROPELLED    VEHICLES. 

tinued  at  a  specified  point.  At  the  first  charging  of  a  cell,  when 
the  pressure  has  reached  the  required  limit,  the  cell  should  be  dis- 
charged until  the  voltage  has  fallen  to  about  two-thirds  normal 
pressure,  when  the  cell  should  again  be  recharged  to  the  normal 
voltage  (2.5  or  2.6  volts). 

Changed  Specific  Gravity  of  the  Electrolyte. — Another  ef- 
fect resulting  from  the  first  charging  of  a  storage  cell  is  a  change 
in  the  specific  gravity  of  the  electrolyte.  According  to  the  fig- 
ures already  given,  this  should  be  about  1,200,  when  the  solution 
is  first  poufed  into  the  cells.  At  the  completion  of  the  first  charge, 
it  should,  on  the  same  scale,  be  about  1,225.  -^  ^  ls  higher  than 
this,  water  should  be  added  to  the  solution  until  the  proper  figure 
is  reached;  if  it  is  lower,  dilute  sulphuric  acid  should  be  added 
until  the  hydrometer  registers  1,225. 

In  charging  a  storage  cell,  particularly  for  the  first  time,  it  is 
desirable  to  remember  that  a  weaker  current  than  that  specified 
may  be  used  with  the  same  result,  provided  the  prescribed  dura- 
tion of  the  process  be  proportionately  lengthened.  The  battery 
may  also  be  charged  beyond  the  prescribed  voltage,  ten  or  twenty 
per  cent,  overcharge  affecting  no  injury  occasionally;  although, 
if  frequently  repeated,  it  seriously  shortens  the  life  of  the  battery. 

Another  point  of  importance  touches  the  question  of  maintain- 
ing the  charge  of  the  battery.  Even  if  the  use  is  only  slight,  in 
proportion  to  the  output  capacity,  the  battery  should  be  charged 
at  least  once  in  two  weeks,  in  order  to  maintain  it  at  the  point 
of  highest  efficiency.  About  as  often  a  battery  should  be  charged 
at  slowest  rate,  the  charging  current  being  adjusted  to  complete 
the  charge  only  in  twenty  or  thirty  hours. 

In  charging  a  storage  battery,  it  is  essential  to  remember  the 
fact  that  the  normal  charging  rate  is  in  proportion  to  the  voltage 
of  the  battery  itself.  Thus,  a  loo-ampere-hour  battery,  charged 
from  a  no  volt  circuit,  at  the  rate  of  ten  amperes  per  hour,  would 
require  ten  hours  to  charge,  and  would  consume  in  that  time  an 
amount  of  electrical  -energy  represented  by  the  product  of  no 
(voltage)  by  10  (hours),  which  would  give  1,100  watts. 

The  Capacity  of  Storage  Batteries. — The  discharge  capacity 
of  a  storage  battery  is  stated  in  ampere-hours,  and,  unless  other- 


STORAGE  BATTERIES. 


513 


wise  specified,  refers  TO  its  output  of  current  at  the  8-hour  rate. 
Most  manufacturers  of  automobile  batteries  specify  only  the 
amperage  of  the  discharge  at  3  and  4  hours.  As  there  is  no  sure 
way  for  the  automobilist  to  estimate  the  discharge-capacity  of 
his  battery,  he  is  obliged  to  base  such  calculations  as  he  makes 
on  the  figures  furnished  by  the  manufacturers.  With  the  help 
of  his  indicating  instruments — the  voltmeter  and  ammeter — this 
is  a  comparatively  simple  matter,  as  may  be  understood  from  the 
following  quotation : 

"It  is  customary  to  state  the  normal  capacity  of  a  cell  in,  am- 
pe-e-hours,  based  upon  the  current  which  it  will  discharge  at  a 
constant  rate  for  eight  hours.  Thus  a  cell  which  will  discharge 
at  10  amperes  for  8  hours  without  the  voltage  falling  below  1.75 
per  cell  is  said  to  have  a  capacity  of  80  ampere-hours.  It  does 


FIG.  376.— Discharge  Curve  of  First  Discharge  in  ±y2  hours  at  20  amperes 
of  a  5  plate,  9-inch  cell  used  for  ignition,  showing  very  gradual  fall  in 
voltage  through  2/$  of  the  period. 


not  follow  that  80  amperes  would  be  secured  if  the  cell 
were  discharged  in  I  hour.  It  is  safe  to  say  that  not  more 
than  40  amperes  would  be  the  result  with  this  rapid  dis- 
charge. The  ampere-hour  capacity  decreases  with  the  increase 
in  current  output.  An  80  ampere-hour  cell,  capable  of  delivering 
TO  amperes  for  8  hours,  would,  when  discharged  at  14  amperes, 
have  a  capacity  of  70  ampere-hours ;  when  discharged  at  20,  its 
capacity  would  be  60;  and  when  discharged  at  40,  its  capacity 
will  have  decreased  from  80  to  40  ampere-hours.  Generally 
speaking,  the  voltage  during  discharge  is  an  indication  of  the 
quantity  of  electricity  remaining  within  the  cell." 

In  order  to  obtain  a  general  idea  of  the  comparative  figures,  as 
between  the  several  makes  of  American  storage  cell,  the  following 
tables  on  sizes  suitable  for  automobile  use  are  given. 


514 


SELF-PROPELLED    VEHICLES. 


The  manufacturer  of  one  of  the  most  efficient  types  of  battery 
gives  the  following  data : 


Discharge  in  Amperes 
Per  Hour  During 

Ampere  Hour  Capacity 
When  Discharged 
in 

Normal 
Charging 
Rate 

Outside  Dimensions  of 
Jar  in  Inches 

8  Hrs.      5  Hrs.      3  Hrs. 

8  Hrs.      5  Hrs.      3  Hrs. 

Height 

Length 

Width 

6X          8X       12/2 

50        43X        37^ 

6* 

10)4 

sX 

4X 

7/2              ™/2            15 

60        52  1/2        45 

7/2 

II 

7% 

4^ 

8*        12*       17/2 

70        61*         52^ 

*X 

12/2 

4X 

10                14               20 

80        70            60 

10 

12 

6/8 

7 

*L2l/2           17^          25 

100        87^         75 

12)4 

12 

7 

15                21               30 

120         105                 90 

15 

12)4 

6^ 

7 

17#        24)4       35 

140         122^          105 

12/2 

6/8 

7 

20                28              40 

I  60         I4O              I  2O 

20 

12/2 

22/2        $1/2       45 

180       157^       135 

22)4 

12/2 

9 

6%. 

25           35          5o 

200          175                150 

25 

12/2 

9 

6)4 

27/2        38/2       55 

220          192^          165 

27/2 

9 

6/2 

30           42          60 

240       210          180 

30 

12)4 

9 

6)4 

37/2        52/2       75 

300     262^      225 

37/2 

12/2 

7X 

45            63          90 

360     315        270 

45 

9 

8^ 

52  /2        73/2     105 

420     367^     315 

52^ 

12/2 

8 

For  another  make  of  battery  the  same  rates  of  discharge  give 
the  following  figures : 


Discharge  in  Amperes 
Per  Hour  During 

Ampere  Hour  Capacity 
When  Discharged 
in 

Normal 
Charging 
Rate 

Outside  Dimensions  of 
Jar  in  Inches 

8  Hrs.      5  Hrs.      3  Hrs 

8  Hrs.      5  Hrs.     3  Hrs. 

Height 

Length 

Width 

7/2                 8/2           15 

60       52)4      45 

7/2 

8/2 

6)4 

9 

75       65^      56  X 

9/8 

8/2 

6%, 

9 

IrX         I5^      22)4 

90       78^      67/2 

8/2 

6)4 

10/2 

10                 14              20 

80       70          60 

10 

12/2 

7 

9 

15                 21               30 

1  20     105          90 

15 

12/2 

7 

9 

2O                 28              40 

l6o        140            I2O 

20 

12/2 

9 

25            35          5o 
30            42          60 

200        175            150 

240     210        180 

25 
30 

12/2 

10 
12/2 

9 
9 

35            49          7o 
40            56          80 

280        245            210 
320        280            240 

35 
40 

15  >2 

12/2 

9 
9 

50            70        100 

400       350            200 

50 

isK 

I2^j 

IO^j 

60            84        120 

480       420           360 

60 

15^ 

I2# 

10^ 

The  variation  in  figures  between  the  two  types  mentioned  is 
largely  due  to  the  number  of  plates  per  jar  and  to  other  points  of 
construction.  Apart  from  any  considerations  of  efficie,ncy,  the 
driver  of  an  electric  carriage  should  carefully  bear  in  mind  the 
figures  supplied  by  the  manufacturers  of  the  type  of  battery  he 


STORAGE   BATTERIES.  515 

uses,  in  order  to  judge  (i)  how  long  the  present  charge  will 
last;  (2)  whether  he  is  exceeding  the  normal  rate  of  discharge, 
and  thus  contributing  to  the  unnecessary  waste  of  his  battery  and 
incurring  other  dangers  that  may  involve  unnecessary  expense. 
As  a  general  rule  the  i-hour  discharge  rate  is  four  times  that  of 
the  normal,  or  8-hour  discharge,  and  considerations  of  economy 
and  prudence  suggest  that  it  should  never  be  exceeded,  if,  indeed, 
it  is  ever  employed.  The  3-hour  discharge,  which  is  normally 
twice  that  of  the  8-hour,  is  usually  the  highest  that  is  prudent, 
while  the  4-hour  discharge  is  the  one  most  often  employed  for 
average  high-speed  riding.  Thus,  most  makers  of  automobile 


FIG.  377.— Elwell-Parker  Motor  Generator  Set  for  Charging  Vehicle  Storage 
Batteries.  This  machine  has  an  output  capacity  of  about  15  horse 
power. 

batteries  give  only  the  3  and  4-hour  discharge  rates  in  specifying 
the  capacity  of  their  products 

High  Charging  Rates. — Occasionally  it  is  desirable  to  charge 
a  battery  as  quickly  as  possible,  in  order  to  save  time,  ,a.s  when 
belated  and  far  from  home  with  an  electric  vehicle  that  has  al- 
most reached  its  limit.  As  a  general,  if  not  an  invariable,  rule, 
such  a  procedure  should  not  be  adopted  unless  the  battery  is 
thoroughly  discharged,  and  not  then,  unless  done  by  a  person 
who  thoroughly  understands  what  he  is. about.  As  battery-mak- 
ers will  always  furnish  data  and  directions  to  meet  emergencies 
demand  rapid  charging,  it  is  unnecessary  to  run  risks. 


516 


SELF-PROPELLED    VEHICLES. 


In  charging  a  battery  at  a  high  rate,  the  danger  to  be  avoided 
is  the  tendency  of  the  cells  to  heat.  The  troubles  that  might  arise 
from  this  cause  may  be  prevented  by  immediately  reducing  the 
current  strength.  The  proper  rate  of  charge  for  a  given  battery 
of  cells  may  be  thus  discovered  by  experiment.  A  battery  should 
never  be  charged  at  a  high  rate  unless  it  be  completely  exhausted, 
since  it  is  a  fact  that  the  rate  of  charge  that  it  will  absorb  is  de- 
pendent upon  the  amount  of  energy  already  absorbed. 

As  given  by  a  well-known  vehicle  manufacturer,  the  following 
data  on  discharging  and  rapid  charging  of  a  given  make  of  bat- 
tery will  be  found  typical : 


Ampere  Hour  Capacity 
Discharged 

if? 

i|«5 

zo 

Rate  in  Amperes  for 
a  3-Hour  Charge 

Rate  in  Amperes  for  a 
45-Minute  Charge 

3Hr.  4Hr.  5  Hr.  6Hr.  8Hr. 

^Hr.^Hr  ^Hr.^Hr.lHr. 

J  20  M.  5V.   5  M.    10  M.  5M. 

34     38     40    42     48 
45     50     53     55     64 
66     73      78    81     96 
112  124    132  137  160 
140  iss    165  171  200 
1  68  1  86    198  206  240 
196  217    231  240  280 

6 

8 

12 
20 
25 
30 

35 

36      20     16     10      5 
48      28     20     1  6      7 
70      40    30     20     10 
128      68    52     32     17 
150      86    62     42     21 
178    102     76     50     26 
208    118     90     60    30 

72      52      36     16      5 
96      68      48     20       7 
140     loo      70     30     10 

238    170   119    51    17 

3OO       214      I5O      64       21 
356       254      178       76       26 
42O      3OO      210       90      30 

As  here  shown,  the  96  ampere-hour  cell  requires,  for  charging 
in  three  hours  :  For  the  first  half  hour,  70  amperes  ;  for  the  second, 
40  amperes;  for  the  third,  30  amperes;  for  the  fourth,  20  am- 
peres, and  during  the  last  hour,  10  amperes.  It  may  also  be 
charged  at  the  following  rate  in  45  minutes :  140  amperes  for  the 
first  20  minutes ;  100  amperes  for  the  next  5  minutes ;  70  am- 
peres for  the  next  5  minutes ;  30  amperes  for  the  next  10  minutes ; 
10  amperes  for  the  last  five  minutes.  This  is  the  rate  to  be  fol- 
lowed when  the  battery  is  completely  discharged. 

Such  figures  would  undoubtedly  vary  for  different  makes  of 
battery,  but,  when  once  known  should  never  be  departed  from, 
except  by  an  expert  who  knows  perfectly  what  he  is  doing  in  any 
given  case.  Such  a  person,  however,  would  likely  be  more  than 
usually  careful  to  observe  rules.  In  fact,  these  rules  are  im- 
perative, and  a  current  of  a  given  strength  should  not  be  con- 
tinued over  the  time  specified  in^the  directions,  nor  after  the  volt- 
meter records  a  pressure  of  2.6  volts  per  cell, 


STORAGE   BATTERIES.  517 

General  Points  on  Care. — It  is  unnecessary  to  give  a  long 
series  of  minute  directions  on  what  to  do  and  what  not  to  do  in 
all  imaginable  conditions.  If  the  user  of  a  storage  battery  will 
always  remember  that  this  apparatus  is  a  very  delicate  one ;  that 
it  will  do  so  much  in  a  given  time,  and  no  more ;  that  it  must  be 
used  and  treated  quite  as  carefully  as  a  living  thing;  that- any  at- 
tempt to  make  it  do  more  than  experts  have  stated  that  it  can 
do  will  only  involve  failure,  disaster  and  expense — perhaps  also 
danger — he  will  have  mastered  the  substance  of  what  the  best- 
worded  treatise  could  tell  him. 

When  charging  a  battery  particular  care  should  be  taken  not  to 
have  a  naked  flame  anywhere  in  its  vicinity.  This  is  necessary 
because  during  that  process  inflammable  gases,  principally  hydro- 
gen, are  given  off,  and  the  result  will  be  more  picturesque  than 
enjoyable.  To  either  discharge  or  charge  a  battery  at  too  rapid 
a  rate  involves  the  generation  of  heat.  Thus,  while  this  is  not 
liable  to  result  in  flame  under  usual  conditions,  the  battery  may 
take  fire,  if  it  is  improperly  connected  or  improperly  used. 

A  well-known  European  authority  specifies  three  reasons  for 
this  accident: 

1 i )  Faulty  connection  of  conductors  leading  to  the  controller. 

(2)  The  use  of  such  a  conductor  that  is  so  long  as  to  lie  over 
the  battery,  so  that  the  insulation  is  rubbed  off,  causing  a  short 
circuit. 

(3)  Short  circuit >  caused  by  acid  splashed   from  the  battery 
eating  the  insulation  of  such  conductors. 

His  directions  are  sensible  and  practical :  ( I )  Set  the  con- 
troller at  rest;  (2)  open  the  switch  or  withdraw  the  emergency 
plug;  (3)  open  the  battery  case  and  disconnect  the  battery  from 
the  rest  of  the  machinery.  This  will  cause  the  fire  to  go  out  of 
itself. 

In  driving  an  electric  vehicle  the  battery  should  be  saved  as 
much  as  possible,  particularly  on  steep  hills  and  rough  roads. 
If  the  amperage  rises  abnormally  on  a  hill  it  is  better  to  tack 
from  side  to  side  than  to  risk  mishaps. 

If  under  such  conditions,  the  voltmeter  shows  a  fall  below 
1.75  per  cell,  it  does  not  necessarily  indicate  that  the  battery  is 
exhausted  or  injured.  However,  a  careful  driver  will  stop  his 
carriage  for  a  few  minutes,  when  it  will  be  probable  that  the 
normal  reading  will  again  be  shown.  If  this  result  follows  often 
in  succession,  the  battery  had  better  be  examined  by  an  expert. 
Generally,  however,  it  is  merely  the  result  of  hard  working. 


518  SELF-PROPELLED    VEHICLES. 

Edison  Battery:  Theory  and  Construction. — The  recently 
perfected  Edison  storage  cell,  although  a  departure  in  several 
particulars  from  the  general  theory  of  electrical  accumulators 
hitherto  recognized,  may  be  classed  with  those  types  of  battery 
constructed  on  the  principle  of  having  the  plates  of  opposite  po- 
larity constructed  of  diverse  materials.  Among  such  may  be 
mentioned  the  so-called  lead-zinc,  lead-copper  and  alkaline-zinc- 
ate,  in  which  one  plate  was  formed  of  zinc,  of  copper,  or  other 
suitable  substance.  None  of  them  has  been  used  in  automobile 
work. 

Following  his  usual  procedure,  Mr.  Edison  started  his  investi- 
gations with  the  theory  that  the  ideal  storage  cell  should  embody 
the  following  peculiarities : 

( I )  An  alkaline  "electrolyte" — all  corrosive  acids  being  elimi- 
nated ;  (2)  active  materials  insoluble  in  the  liquid;  (3)  a  solution 
that  should  remain  the  same  under  all  conditions;  (4)  immunity 
from  deterioration  or  disintegration  in  use;  (5)  simplicity  in  the 
process  of  charging;  (6)  immunity  from  injury  by  overcharging 
or  overdischarging ;  (/)  a  high  rate  of  charge  and  discharge; 
(8)  small  weight  per  horse  power  per  hour  and  constant  dis- 
charge capacity  through  extended  periods. 

As  the*  result  of  investigations  with*  a  wide  variety  of  sub- 
stances, Mr  Edison  finally  constructed  a  cell  with  an  oxide  of  iron 
for  the  negative  element,  and  a  superoxide  of  nickel  for  the 
positive,  with  a  solution  containing  about  twenty  per  cent,  of  po- 
tassium hydroxide  by  weight. 

Mechanically,  also,  the  construction  differs  from  ordinary  ac- 
cumulators. Each  grid,  or  plate,  formed  of  steel,  has  twenty-four 
rectangular  openings,  giving  it  somewhat  the  apearance  of  a  win- 
dow. Into  each  of  these  is  fitted  and  pressed  a  flat  box  or  pocket 
—the  one  part  of  which  engages  into  the  other,  like  a  box  and 
cover,  each  being  thoroughly  perforated.  The  active  material 
is  placed  in  these  boxes,  the  nickel  in  those  of  one  grid,  the  iron 
in  those  of  the  other.  The  construction  is  thus  extremely  light 
and  compact. 

The  Theory  of  Operation. — In  operation,  the  theory  involved 
is  simply  the  transfer  of  oxygen  from  one  material  to  the  other — 
from  the  nickel  to  the  iron  in  charging,  and  from  the  iron  to  the 
nickel  in  discharging.  The  solution  furnishes  merely  a  suitable 
means  of  transfer. 

Data  on  Charging  and  Discharging. — The  several  sizes  of 
cell,  as  at  present  manufactured,  differ  only  in  the  number  of 


STORAGE,   BATTERIES. 


519 


plates  and  in  capacity,  the  dimensions  of  the  plates  being  the  same 
in  each  case.  The  following  table  gives  the  general  data  relating 
to  the  sizes  of  cell  suitable  for  automobile  work : 


Number  of  Plates. 

E-18. 

E-27. 

E-45. 

105  to  115 

160  to  175 

260  to  280 

Average  discharge  voltage  per  cell.... 
Rates  of  discharge  in  amperes  
Satisfactory  rates  of  charging  in  am- 
peres                       

1.23 
30 
40 

1.23 
45 
65 

1.23 
75 
100 

Suitable  times  of  charging  in  hours... 
Weights  in  pounds  per  cell  complete, 

3tf 

13 

3M 

17  IX 

3M 
28 

As  may  be  seen,  the  average  discharge  voltage  is  lower  than 
in  other  types  of  cell,  the  available  pressure  being,  in  fact,  cut 
down  fifty  per  cent.  The  advantage  realized,  however,  is  in  du- 
rability, rather  than  in  high  capacity.  A  battery  of  32  such  cells, 
rating  160  ampere-hours,  will  give  at  a  3O-ampere  discharge  a 
travel  radius  of  40  miles  at  15  miles  per  hour  for  a  light  runa- 
bout. In  relation  to  its  weight,  however,  the  Edison  cell  is  very 
much  more  powerful  than  the  average  of  other  types.  Accord- 
ing to  the  data  furnished  by  Professor  Kennelly,  the  average 
lead-lead  cell  yields  between  4  and  6  watt-nours  per  pound 
weight,  which  is  between  124.5  ar|d  186.5  pounds  per  horse- 
power hour  at  its  terminals,  or  an  energy  sufficient  to  raise  its 
own  weight  through  a  vertical  distance  of  from  2  to  3  miles  (3.2 
to  4.8  kilometres)  against  the  force  of  gravity.  The  Edison  bat- 
tery, on  the  other  hand,  yields  14  watt-hours  per^  pound  weight, 
which  is  about  53.3  pounds  per  horse-power  hour  at  its  terminals, 
or  an  energy  sufficient  to  raise  its  own  weight  through  a  vertical 
distance  of  7  miles  (11.26  kilometres). 

It  also  embodies  the  advantages  of  being  virtually  uninjured 
by  overcharge  or  overdischarge,  and  of  requiring  no  other  ordin- 
ary care  than  the  occasional  addition  of  pure  water  to  maintain 
the  proper  level  of  the  solution  in  the  jars. 

Battery=Charging  Apparatus. — A  storage  battery  may  be 
charged  from  direct-current  mains  having  the  proper  voltage  if, 
as  is  not  always  possible,  such  a  circuit  is  available."  Since,  how- 
ever, a  current  of  as  great  uniformity  as  possible  is  required,  and 
existing  conditions  must  be  met  in  each  separate  case,  it  is  the 
rule  to  use  a  motor-generator  set  with  a  regulating  switchboard. 
Such  an  apparatus  consists  of  a  direct-current  dynamo,  driven 
direct  from  the  shaft  of  a  motor,  which,  in  turn  is  energized  by 
current  from  the  line  circuit.  With  a  direct  current  on  the  line, 


520 


SELF-PROPELLED    VEHICLES. 


a  direct-current  motor  may  be  used ;  but  with  an  alternating  cur- 
rent an  induction  motor  is  required.  The  speed  of  the  motor  is 
governed  by  a  theostat,  and  the  output  of  the  dynamo  is  thus 
regulated  as  desired. 


FIG.  378.— Waverley  Motor-generator  Charging  Set  for  Use  on  a  Single- 
phase  Alternating  Current  Circuit  of  100  to  110  Volts  (60  Cycles).  This 
apparatus  will  give  a  current  of  15  amperes  at  65  volts  in  charging  a 
24-cell  battery,  or  10  amperes  in  charging  a  30-cell  battery. 

A  typical  outfit  of  this  description  is  shown  in  the  accompany- 
ing diagrams,  which  show  the  circuits  of  a  switchboard  and 
charging  set,  operated  from  both  direct  and  alternating-current 
line  circuit.  The  switchboards  are  equipped  with  a  voltmeter 
for  indicating  the  pressure  of  the  generator ;  an  ammeter  for  in- 
dicating the  amount  of  current  being  supplied  to  the  batteries; 


STORAGE  BATTERIES. 


521 


an  underload  coil  to  automatically  shut  down  the  motor-gener- 
ator set  when  the  battery  is  fully  charged ;  a  low-voltage  coil,  to 
open  the  circuit  on  the  moment  of  cutting  off  the  power,  thus 
fully  protecting  the  motor,  preventing  the  battery  from  running 
the  dynamo  motorwise  and  involving  that  the  starting  theostat  be 
used  whenever  the  motor  is  to  be  used.  These  operations  may  be 
performed  manually  by  the  use  of  circuit-breaking  handles. 

Method  of  Operating. — An  idea  of  the  procedure  involved  in 
the  use  of  such  an  apparatus  may  be  obtained  from  the  following 
items  furnished  by  the  General  Electric  Company's  outfits: 


L'ne- 1    I  I 

L       L         Circuit          I 
tO»tt»/6oaeJ       )~  Breaker    -» 


OC  m0t. 


OC.&enerotor 


FIGS.  379,  380.— Switchboard  and  Motor-generator  Circuit  Connections  for  Charg- 
ing a  Battery  from  Direct  Current  Mains. 

(1)  Pull  down  the  tripping  handle  of  the  circuit  breaker  and 
close  the  two  outside  poles  which  connect  the  motor  circuit.    The 
tripping  shaft  is  then  automatically  locked  so  that  the  breaker 
will  not  reopen.     Then  push  the  core  of  the  low-voltage  coil 
(right-hand  coil)  up  as  far  as  it  will  go. 

(2)  Start  the  motor. 

(3)  Regulate  the  generator  to  give  about  the  desired  charging 
voltage. 

(4)  Connect  cable  to  automobile  and  attach  to  panel  by  means 
of  plug  switch. 

(5)  Raise  the  core  of  the  underload  coil   (left-hand  coil)   up 
as  high  as  it  will  go,  and  while  holding  in  this  position  close  the 


522 


SHIP-PROPELLED   VEHICLES. 


other  two  poles  of  the  circuit  breaker.  The  closing  of  these  two 
poles  releases  the  lock  on  the  tripping  shaft  so  that  the  breaker 
will  then  operate  on  either  underload  or  low  voltage. 

(6)  Regulate  generator  voltage  until  ammeter  indicates  the 
normal  ampere  charging  rate  of  the  storage  battery. 

Dynamos  are  also  furnished  with  a  small  gas  engine,  the  speed 
being  regulated  by  adjusting  the  intake  of  fuel,  and  the  pressure 
and  current  by  a  suitable  switchboard. 


"Tf 


oj't  Breaker 


Plug  Sw/tcA 


FIGS.  381,  382.— Switchboard  and  Motor-generator  Circuit  Connections  for 
Charging  a  Battery "  from  Alternating  Current  Mains.  The  connections 
of  a  third  wire  are  shown,  for  use  in  case  a  three-phase  circuit  is 
available. 


CHAPTER    THIRTY-TWO. 

STEAM   AND    ITS    USE   AS   A   MOTIVE   POWER. 

The  General  Situation  on  Steam  Using. — In  recognizing 
and  applying  practically  the  fact  of  the  expansive  energy  of 
steam,  Watt  earned  his  title,  inventor  of  the  steam  engine.  All 
that  has  been  done  since  his  day  is  to  still  further  enlarge  on 
the  principles  applied  by  him :  First,  in  the  use  of  higher  pres- 
sures; second,  in  such  structural  improvements  as  have  ren- 
dered steam-using  more  economical  and  brought  the  engine  to 
the  high  point  of  perfection  it  now  possesses.  All  these  im- 
provements in  the  direction  of  enlarged  efficiency  have  been 
made  possible  by  a  more  perfect  knowledge  and  closer  observa- 
tion of  the  laws  governing  the  properties  of  steam  at  various 
temperatures  and  pressures.  For,  although  exhibiting  divergent 
properties  in  some  particulars,  steam  may  be  treated  and  handled 
according  to  the  general  laws  of  "permanent"  gases — those, 
such  as  air,  oxygen,  etc.,  which  never  pass  into  the  liquid  or 
solid  states  under  the  natural  physical  conditions  maintaining 
on  the  earth's  surface. 

On  Steam  and  Other  Oases. — In  treating  of  gases  in  gen- 
eral, we  must  bear  in  mind  that  modern  science  has  apparently 
succeeded  in  artificially  producing  liquid  carbonic  acid  gas  and 
"liquid  air" ;  but  these  results,  as  is  well  known,  are  achieved 
by  the  production  of  certain  physical  conditions  which  occur 
naturally  at  no  place  on  earth.  While  not  digressing  so  far  as 
to  attempt  a  description  of  the  laboratory  processes  employed, 
it  is  not  too  much  to  say  that  the  results  are  achieved  by  com- 
binations of  extremely  high  pressures  and  extremely  low  tem- 
peratures,, such  as  must  necessitate  complete  readjustment  of 
molecular  conditions  in  the  gases  treated.  Just  as  permanent 
liquids,  such  as  water  and  mercury,  assume  the  solid  state  at  suf- 
ficiently low  temperatures,  and  just  as  permanent  solids,  such  as 
iron  and  flint,  will  assume  the  liquid  state  under  sufficiently  high 
temperatures,  so  "permanent  gases"  become  liquids  when  the 
produced  conditions  are  favorable.  When,  on  the  other  hand, 


524 


SELF-PROPELLED    VEHICLES. 


the  physical,  or  molecular,  state  of  a  substance  is  changed,  the 
continuance  of  the  new  state  depends  upon  the  maintenance  of 
the  conditions  in  which  it  was  produced.  Thus,  when  water  is 
changed  into  the  vapor  known  as  "steam/'  by  the  action  of  heat, 
it  will  return  to  the  liquid  state  if  the  temperature  is  allowed  to 
fall  sufficiently.  For  this  reason,  it  is  necessary  to  maintain  the 
cylinders  of  a  steam  engine  at  a  temperature,  at  least,  equal  to 
that  of  the  incoming  steam.  For  this  reason,  also,  it  is,  in  gen- 
eral, impracticable  to  use  steam  of  too  high  pressures — the  pres- 
sure and  temperature  rise  on  a  certain  proportional  scale — since, 


FIG.  383.  -A  Simple  Form  of  Steam  Separator.  The  steam,  admitted  through  ths  port  at 
the  left  of  the  figure,  strikes  against  the  screen  in  the  centre  of  the  chamber,  thence 
following  the  direction  of  the  arrows.  Any  condensation  settles  in  the  bottom  of  the 
chamber,  whence  it  may  be  drawn  off  by  the  ports  there  shown. 

as  cannot  be  avoided,  the  difference  between  its  temperature 
and  that  of  the  cylinder  walls  is  so  great  that,  during  the  period 
of  exhaust,  a  large  part  of  it  is  condensed ;  which  means  that  the 
advantage  gained  will  sooner  or  later  be  counteracted.  This 
brings  us  to  a  consideration  of  the  principles  governing  the  gen- 
eration and  use  of  steam. 

The  Conditions  of  Steam  Generation. — According  to  the  cur- 
rent hypothesis  on  the  constitution  of  matter,  a  very  essential 
difference  between  the  liquid  and'gaseous  states  of  matter  is  that, 


STEAM  AND   ITS  USE.  525 

in  passing  from  the  first  to  the  second,  the  constituent  molecules 
of  the  substance  are  forced  further  apart.  This  seems  to  explain 
the  fact  that,  when  a  liquid  passes  into  a  gas,  it  not  only  "evapor- 
ates" and  disappears,  but  also  fills  a  very  much  larger  cubic 
space.  Moreover,  the  amount  of  this  expansion — as  measured 
by  the  cubic  content  filled  by  the  gas,  as  compared  with  that  filled 
by  the  liquid — is  in  proportion  to  the  'heat  under  the  action  of 
which  the  water  is  vaporized.  If  then,  a  gas  subjected  to  heat  be 
confined  in  some  receptacle,  so  that  it  cannot  occupy  the  space 
properly  belonging  to  it,  it  will  show  its  tendency  to  assume  that 
volume  by  exerting  a  pressure  in  proportion  to  the  temperature 
in  the  receptacle.  This  is  precisely  what  happens  in  a  steam 
boiler.  The  steam,  when  liberated  from  confinement,  will  con- 
tinue to  exert  a  constantly  decreasing  pressure,  until  it  has 
reached  the  volume  properly  resulting  from  its  temperature,  at 
which  point  the  pressure  will  be  that  of  the  atmospheric  air.  It 
is  this  pressure,  or  natural  effort  to  assume  a  greater  volume — 
hence  to  displace  movable  obstacles — that  is  employed  in  the 
steam  engine  for  producing  motion  and  transmitting  power. 

The  Forms  of  Steam. — In  dealing  with  the  general  problems 
of  steam  engine  operation,  we  must  recognize  two  kinds  of 
steam,  or  rather  two  conditions  in  which  it  is  found  and  used. 
The  first  is  that  known  as  "saturated"  steam,  which  may  be  de- 
fined as  steam  in  contact  with  the  water  from  which  it  has  been 
generated,  and  which  has  absorbed  and  holds,  as  "latent  heat," 
the  full  number  of  thermal  units  necessary  to  completely  vapor- 
ize the  liquid  at  the  given  pressure.  The  significance  of  the  word, 
"saturated,"  is  thus  apparent — the  steam  holds  in  solution  the  full 
quantity  of  heat  theoretically  needed  to  produce  and  maintain  it 
as  steam.  The  second  distinction  of  steam  is  "separated"  steam, 
which  signifies  steam  mechanically  separated  from  the  generat- 
ing liquid,  so  that,  when  fed  to  the  cylinder  of  the  engine,  it  is  per- 
fectly dry.  As  the  process  of  separation  properly  involves  the  con- 
stant maintenance  of  a  high  temperature,  so  that  the  process  of 
condensation  may  be  prevented,  the  dry  steam  continues  to  ab- 
sorb heat,  above  the  point  required  for  this  end,  and  thus  be- 
comes what  is  known  as  "superheated"  steam. 

When  steam  is  properly  separated  and  superheated,  its  expan- 
sion and  other  properties,  so  long  as  the  initial  temperature  is 


526  SELF-PROPELLED    VEHICLES. 

maintained,  follows  closely  on  the  laws  governing  the  actions  of 
permanent  gases.  This  is  true  only  in  a  limited  sense  of  steam 
that  is  still  in  contact  with  the  generating  liquid ;  since,  not  only 
does  increase  of  heat  within  the  generator,  or  boiler,  tend  to  con- 
tinue the  process  of  steam  production  within  small  limits,  but  also 
because  the  steam  holds  in  suspension  a  certain  amount  of  un- 
vaporized  liquid  particles.  From  either  or  both  these  causes,  its 
coefficient  of  expansion  is  larger  than  that  of  dry  steam.  That 
is  to  say,  it  undergoes  a  greater  increase  in  potential  volume,  as 
indicated  by  the  consequent' rapid  proportionate  increase  in  pres- 
sure, within  the  generator,  or  heated  receptacle.  Another  point 
of  difference — here  it  is  that  dry  steam  assumes  the  general 
properties  of  permanent  gases — is  that  saturated  steam,  when  a 
certain  high  point  of  pressure  has  been  reached,  tends  to  liquefy ; 
hence  also  preventing  the  heated  water  from  giving  off  any  more 
vapor.  Dry  steam  may  not  be  condensed  by  pressure,  so  long  as 
the  temperature  is  not  lowered.  On  account  of  this  law  of  pres- 
sures, the  evaporation  of  water  by  the  sun,  under  atmospheric 
conditions,  is  less  rapid  than  at  high  temperatures ;  also,  water 
enclosed  in  a  vacuum  tube,  where  it  is  subjected  to  no  pressure, 
theoretically,  may  be  boiled,  producing  vapor,  at  the  temperature 
of  the  human  body  (96°  Fahrenheit). 

The  Law  of  Pressure  and  Volume  of  Gases. — The  physical 
properties  of  gases  in  general  are  defined  by  two  familiar  laws 
— the  first  defining  the  degrees  of  volume  and  pressure  at  con- 
stantly maintained  temperatures ;  the  second,  the  ratio  of  expan- 
sion at  a  constantly  increasing  temperature.  The  first,  known  as 
Boyle's  Law,  states  that  THE  VOLUME  OF  A  GAS  VARIES  IN- 
VERSELY AS  THE  PRESSURE,  SO  LONG  AS  THE  TEMPERATURE 
REMAINS  THE  SAME;  OR,  THE  PRESSURE  OF  A  GAS  IS  PRO- 
PORTIONAL TO  ITS  DENSITY. 

This  law  has  frequently  been  illustrated  by  the  following  ex- 
periment : 

If  we  take  a  hollow  cylinder,  such  as  is  used  on  steam  engines, 
having  a  piston  sliding  airtight  in  its  length,  we  will  find  that  the 
contained  air,  or  other  gas,  is  compressed  in  front  of  the  piston, 
as  it  is  forced  from  one  end  toward  the  other  of  the  base,  and 
that  this  air,  or  gas,  exerts  a  pressure  which  increases  in  ratio  as 
the  volume  is  diminished.  This  fact  may  be  shown  by  inserting 


STEAM  AND    ITS  USE. 


527 


in  the  wall  of  the  cylinder  a  tube  containing  an  airtight  piston, 
upon  which  bears  a  spiral  spring  holding  it  normally,  as  at  A; 
the  pressure  there  being  supposedly  equal  on  both  sides  of  the 
piston,  or  equivalent  to  15  pounds  per  square  inch.  If,  now,  the 


FIG.  384.  —Diagrammatic  Section  of  a  Cylinder  illustrating  the  compression  and  expan- 
sion of  gases.  This  cylinder  is  filled  with  air  at  atmospheric  pressure  which  repre- 
sents a  uniform  14.7  pounds  to  the  square  inch  behind  the  piston,  as  shown  by  the 
position  ol  the  piston  in  the  small  cylinder,  A.  When  the  piston  of  the  large  cylinder 
is  moved  through  half  the  length  of  the  stroke,  it  shows  30  pounds  pressure,  as  shown 
by  the  position  of  the  piston  in  small  cylinder,  B;  when  at  three-quarters  stroke,  60 
pounds,  as  shown  by  position  of  the  piston,  C;  when  at  seven-eighths  stroke,  120 
pounds,  as  shown  by  position  of  piston,  D.  At  full  stroke  it  would  be  240  pounds,  the 
diagram  behind  the  small  piston  giving  the  compression  curve  from  16  to  240. 

area  of  this  small  piston  be  exactly  one  square  inch,  and  the 
spring  of  such  a  tension  as  to  move  upward  through  one  of  the 
spaces  between  the  lines  on  the  diagram  behind  the  large  cylin- 


528 


SELF-PROPELLED    VEHICLES. 


der  with  each  ten  pounds  of  added  pressure  from  below,  the  re- 
sult will  be  as  follows :  When  the  piston  of  the  large  cylinder  has 
been  pushed  through  one-half  its  length,  the  depression  of  the 
spring  in  the  smaller  one  will  show  that  the  pressure  is  just  twice 
what  it  was  at  the  start,  or  30  pounds.  At  three-quarters  the 
stroke  it  will  show  60  pounds,  and  at  seven-eighths,  120  pounds. 
If  the  four  smaller  cylinders  be  arranged  in  the  wall  of  the  cylin- 


FIG.  385.  — A  Typical  Steam  Engine  Indicator.  It  consists  of  a  cylinder,  shown  at  the 
right,  within  which  works  a  piston  under  tension  of  a  helical  spring  of  predetermined 
strength.  The  rod  attached  to  the  piston  carries  a  pivoted  arm  which  works  on  the 
horizontal  lever,  shown  at  the  top  of  the  cylinder.  This  lever  carries  a  pencil  bearing 
against  the  rotatable  drum,  shown  at  the  left.  This  drum  is  so  arranged  with  a  spring 
that  it  may  be  rotated  by  the  pull  on  the  attached  string.  A  sheet  of  paper  is  wound 
on  the  drum  and  held  in  place  by  the  spring  clips.  The  steam  pressure  in  the  cylinder 
acting  on  the  spring  enables  the  pencil  to  mark;  the  indicator  card  being  traced  by 
the  rotative  movement  of  the  paper  drum. 

der,  as  in  the  accompanying  diagram,  the  difference  in  pressure 
at  these  several  points  may  be  graphically  represented.  Then  a 
curve,  drawn  so  as  to  pass  through  the  centre  of  each  of  the 
-smaller  pistons,  will  give  an  accurate  average  of  pressure  for 
every  position  of  the  large  piston.  On  the  other  hand,  as  under 
the  operative  conditions  in  a  steam  engine,  it  will  represent  the 


STEAM  AND  ITS  USE. 

"curve  of  expansion,"  or  the  decrease  in  pressure  from  the  mo- 
ment of  "cut-off,"  when  the  inlet  valve  is  closed  to  the  end  of  the 
stroke,  when  the  exhaust  valve  is  opened.  If,  therefore,  steam  be 
fed  into  the  cylinder  at  200  pounds  pressure  per  square  inch,  and 
the  inlet  be  closed  when  the  piston  has  traversed  one-eighth  of 
the  stroke,  the  pressure  will  stand  at  100  pounds  on  quarter- 
stroke  ;  at  50  pounds  on  half-stroke,  and,  at  25  pounds  on  the 
point  of  completed  stroke,  which  shows  that  it  is  expanded  four 
times. 

The  Steam  Engine  Indicator  and  Its  Records.* — The  action  of 
the  small  cylinders  containing  springs  and  pistons,  as  just  ex- 
plained, very  well  illustrates  the  operation  of  the  steam  indi- 
cator. With  the  simplest  form  of  this  instrument  these  cylinders 
are  identical,  except  for  a  pencil  carried  on  the  uppermost  end  of 
the  piston  rod,  and  bearing  upon  a  suitable  tablet,  which  is 
moved  backward  and  forward  with  the  stroke  of  the  steam  pis- 
ton. This  is  done  by  attaching  the  long  arm  of  a  reducing  lever 
to  the  crosshead,  and  the  shorter  arm  to  a  link-bar  which  holds 
the  card,  or  tablet,  to  be  inscribed.  The  several  forms  of  the  in- 
dicator most  often  used  at  the  present  day  have  a  rotatable  drum, 
which  is  attached  by  a  cord  to  the  short  arm  of  the  reducing 
lever,  so  as  to  be  turned  in  one  direction;  being  moved  in  the 
other  direction  by  a  contained  spring,  which  rewinds  the  cord, 
so  soon  as  the  lever  arm  moves  backward.  Thus  the  records 'of 
a  great  number  of  strokes  may  be  taken  on  one  sheet  of  paper — 
wound  about  the  drum  and  held  on  by  clips — and  there  is  no 
danger  of  interrupting  the  process. 

The  records  thus  made,  by  knowing  the  dimensions  of  the  cyl- 
inder and  the  tension,  or  resisting  strength,  of  the  steam-actu- 
ated spring,  may  be  very  accurately  calculated  for  the  entire 
cycle  of  the  engine. 

The  Temperature  and  Volume  of  Oases. — While  it  will  be 
hardly  necessary  to  go  into  minute  details  regarding  the  laws  of 
gases,  it  will  be  well  to  briefly  state  the  ascertained  conditions  by 
which  the  volume  is  increased  while  the  pressure  remains  con- 
stant. Thus  the  "second  law  of  gases,"  called  Charles'  or  Gay 
Lussac's  law,  states  that  AT  CONSTANT  PRESSURE  THE  VOLUME 

OF  A   GAS   VARIES   WITH   THE   TEMPERATURE,    THE    INCREASE    BE- 


530  SELF-PROPELLED    VEHICLES. 

ING      IN       PROPORTION      TO      THE      CHANGE      OF      TEMPERATURE 

AND  THE  VOLUME  OF  THE  GAS  AT  ZERO.  By  actual  ex- 
periment it  has  been  ascertained  that  a  gas  increases  on  a 
ratio  of  i-493<i  part  of  its  volume  at  32°  Fahrenheit,  with  each 
additional  degree  added  to  its  temperature.  This  places  the  "ab- 
solute zero,"  or  the  point  at  which  a  gas  would  assume  its 
greatest  possible  density  at  —  461°,  Fahrenheit,  or  —  273°, 
Centigrade.  A  higher  degree  of  temperature  within  a  closed  re- 
ceptacle, like  a  steam  boiler,  involves  a  higher  degree  of  pressure 
there,  and  in  the  cylinder  to  which  the  steam  is  fed,  because  of 
the  tendency  to  assume  a  greater  proportional  volume,  al- 
though, because  of  the  several  inevitable  sources  of  lost  heat, 
no  rule  applies  completely  in»the  practical  operation  of  the  steam 
engine. 

Determining  the  Temperature  From  the  Pressure. — Tables 
showing  the  "properties  of  saturated  steam,"  as  far  as  regards 
the  volume,  temperature,  pressure,  etc. ,  are  given  in  many  books, 
but  the  full  determination  of  these  points  is  a  matter  of  some 
exactness  of  calculation.  In  order  to  explain  the  process  for  a 
given  diagram,  say  like  the  one  already  found  for  a  cylinder  ex- 
panding i-io  pound  of  steam  from  120  pounds  per  square  inch 
pressure  to  atmosphere,  we  can  do  no  better  than  quote  from 
Forney's  "Catechism  of  the  Locomotive/'  He  says :  "If  the  pis- 
ton stand  at  the  point  shown  in  the  previous  figure,  and  i-io 
pound  of  water  be  put  into  the  cylinder,  and  heat  be  applied  to 
it,  it  would  be  necessary  to  heat  the  water  to  212°  before  it  would 
boil.  To  represent  this  heat,  the  vertical  line,  JK,  is  extended 
below  the  horizontal  line,  AJ.  To  heat  i-io  pound  of  water  to 
212°  takes  21.2  units  of  heat," — since  one  unit  of  heat  is  re- 
quired to  raise  one  pound  of  water  at  39°  Fahrenheit  to  one  de- 
gree above — "which  is  laid  off  from  J  to  /'  to  the  scale  repre- 
sented by  the  horizontal  lines.  But,  as  is  shown  in  the  table  in 
the  appendix,  after  the  water  begins  to  boil,  96.6  more  units  of 
heat  must  be  added  to  it  to  convert  it  all  into  steam  of  atmos- 
pheric pressure.  This  number  of  units  of  heat  is,  therefore,  laid 
off  from  /'  to  /".  If  the  piston  be  moved  to  E,  the  middle  of  the 
cylinder,  and  i-io  pound  of  water  is  again  put  into  it,  and  it  is  all 
converted  into  steam,  it  will  have  a  pressure  of  30  pounds  per 
square  inch,  as  it  occupies  only  half  the  volume  that  the  same 


STEAM  AND   ITS  USE. 


531 


quantity  of  steam  did  before.  To  make  water  boil  under  a  press- 
ure of  30  pounds,  it  must  be  heated  to  a  temperature  of  250.4°, 
which  in  this  case  will  require  25  units  of  heat,  .which  is  laid  down 
from  E  to  £'.  To  convert  the  water  into  steam,  after  it  begins 
to  boil,  will  require  93.9  more  units  of  heat,  which  is  also  laid 
down  from  E'  to  E".  In  the  same  way  the  total  heat  to  boil  and 
convert  i-io  pound  of  water  into  steam  at  60  and  120  pounds 
pressure,  as  shown  in  the  appendix,  is  laid  down  on  C  C"  and 
B  B",  and  the  two  curves,  B'  C  E'  /'  and  B"  C"  E"  /",  are  drawn 
through  the  points  which  have  been  laid  down*.  The  vertical  dis- 
tance of  the  one  curve  from  A  J  represents  the  heat  units  re- 


FIG.  386.  -Diagram  showing  the  number  of  heat  units  required  to  raise  one-tenth  pound 
of  steam  under  the  various  pressures  indicated  by  the  position  of  the  piston,  at  full 
stroke,  half  stroke  and  seven-eighths  stroke.  In  using  this  diagram  it  is  necessary 
to  note  that  the  heat  units  are  calculated  from  —1°  Fahrenheit,  instead  of  from  39°, 
as  is  the  general  rule. 


quired  to  boil  i-io  pound  of  water  at  the  pressures  indicated  by 
the  curve  in  the  previous  figure,  and  the  vertical  distance  of  the 
second  curve  from  A  J  represents  the  total  units  of  heat  re- 
quired to  convert  i-io  pound  of  water  into  steam  of  a  volume  in- 
dicated by  the  horizontal  distance  of  any  point  of  the  curve  from 
A  A" ,  and  when  pressure  is  indicated  by  the  expansion  curve 
above.  This  curve  and  the  heat  diagram  may  be  very  conveni- 
ently combined  by  adding  the  latter  below  the  vacuum  line  of  the 
former.  The  relation  of  the  volume  pressure  and  total  heat  is 
thus  shown  very  clearly." 


532  SELF-PROPELLED    VEHICLES. 

The  Practical  Effects  of  Steam  Expansion. — A  principle  rec- 
ognized as  fundamental  in  steam  engine  practice  is  that  the 
work-producing,  or  dynamic,  property  of  a  gas  depends  solely 
upon  its  temperature.  This  is,  substantially,  a  statement  of 
Joule's  law,  which  compares  the  temperature  of  a  gas,  enabling  it 
to  exert  a  certain  amount  of  power,  to  the  stored  energy  repre- 
sented in  a  body  of  a  certain  weight  raised  to  a  certain  height 
above  the  ground.  The  body,  in  falling  under  the  force  of 
^gravity,  obtains  a  certain  degree  of  acceleration,  constantly  in- 
creasing, by  which  the  weight  falling  through  the  given  distance 
is  transformed  into  a  force  capable  of  producing  a  commensurate 
effect  of  impact  on  reaching  the  earth's  surface.  This  potential 
energy  of  a  substance,  represented  either  by  an  acquired  tem- 
perature or  some  analogous  physical  condition,  which,  under 
favorable  circumstances,  would  enable  the  production  of  a  defi- 
nite amount  of  work,  is  known  as  "entropy."^  Could  the  whole 
power  of  a  heated  gas  be  realized  in  its  expansion — which  is  to 
say,  could  its  expansion  be  perfectly  "adiabatic,"  or  "isentropic," 
involving  neither  gain  nor  loss  of  heat  in  the  process — we  should 
have  a  theoretically  perfect  expansion  curve  on  the  practical 
steam  engine.  This  is  .impossible,  however,  with  the  best  ar- 
rangements yet  contrived.  Hence  it  is  that  the  expansion 
curves  of  all  engines  fall  far  below  what  is  demanded  by  theory 
from  the  original  temperature  and  pressure  of  the  steam,  which 
involves  that  the  final  volume  and  the  actual  work  accom- 
plished are  correspondingly  diminished. 

To  quote  from  an  authority  on  steam  engines,  "as  we  can- 
not take  into  consideration  all  the  conditions  which  govern 
and  modify  the  cycle  of  any  motor,  the  usual  practice  is  to  calcu- 
late the  power  on  the  assumption  that  all  theoretical  conditions 
are  complied  with,  and  then  modify  the  result  by  a  certain  co- 
efficient of  efficiency  which  practice  has  established  for  the  par- 
ticular type  of  motor  under  consideration." 

The  Indicator  Diagram  and  the  Engine  Cycle. — The  opera- 
tive efficiency  of  an  engine  may  be  very  well  determined  from 
the  indicator  diagram,  which  gives  a  pictorial  representation  of 
the  internal  conditions  throughout  the  entire  cycle  of  opera- 
tions. As  given  by  a  noted  authority,  already  quoted,  the  dia- 
gram tells  us  eleven  different  things  essential  to  be  known ; 


STEAM  AND   ITS  USE.  533 

(i)  It  gives  the  initial  pressure,  or  the  pressure  at  beginning  of 
the  stroke.  (2)  It  tells  whether  the  pressure  is  increased  or  di- 
minished during  the  period  of  admission.  (3)  It  gives  the  point  ' 
of  cut-off,  when  the  valve  is  closed  and  expansion  begins.  (4) 
It  indicates  the  rate  and  pressure  of  expansion  during  the  whole 
period  of  expansion.  (5)  It  gives  the  "point  of  release,"  when 
the  exhaust  is  opened.  (6)  It  shows  the  rapidity  of  the  exhaust. 
(7)  It  gives  the  degree  of  back-pressure  on  the  piston,  due  to  the 
exhaust  having  closed,  preventing  further  expansion.  (8)  It 
shows  the  point  of  closing  the  exhaust.  (9)  It  shows  the  com- 
pression of  the  residual  steam  in  the  clearance  after  closing  the 
exhaust.  (10)  It  gives  the  mean  power  used  in  driving  the  en- 
gine, (u)  It  indicates  any  leakage  of  valves  or  piston. 


±^:i^>- 


Fig.  387  —Diagram  of  the  Cycle  of  a  Steam  Engine.  The  dotted  circle  indicates  the  path 
of  the  crank;  the  arrow,  the  direction  of  rotation.  The  admission  begins  a  little  be- 
fore the  completion  of  the  stroke;  the  cut-off  is  set  somewhat  less  than  quarter- 
stroke;  release,  or  opening  of  the  exhaust,  at  somewhat  over  half  stroke;  closing  of 
the  valve  at  the  point  marked  "  compression,"  after  which  the  steam  behind  the 
piston  is  compressed  in  the  clearance  until  the  opening  of  the  inlet  valve. 

The  cycle  of  operations  in  a  steam  cylinder  consists  of  four 
stages:  (i)  Admission;  (2)  expansion;  (3)  exhaust;  (4)  compres- 
sion. 

The  indicator  card  (Fig.  232),  which  is  drawn  to  illustrate  the 
average  conditions  in  an  efficient  low-pressure  cylinder,  shows 
the  pressures  at  various  points  in  the  cycle.  At  line  i,  the  press- 
ure of  the  steam  in  entering  the  cylinder  is  shown  rising  from 
a  point  of  no  pressure  to  57  pounds,  the  curve  in  the  vertical  line 
indicating  a  back  pressure  of  at  least  three  pounds  at  the  be- 
ginning of  the  admission,  as  shown  by  the  fact  that,  at  line  2,  the 
pressure  stands  at  60  pounds,  and,  at  line  3,  just  after  the  closure 
of  the  admission  valve,  at  58  pounds.  The  engine  from  which 


534 


SELF-PROPELLED    VEHICLES. 


this  diagram  is  taken  has  its  cut-off  at  a  point  somewhat  less 
than  quarter  stroke.  After  the  point  of  cut-off,  the  pressure  falls 
steadily,  as  indicated  by  the  droop  of  the  expansion  line,  until 
at  ordinate,  10,  it  shows  13.75  pounds  to  the  square  inch.  At  this 
point  the  exhaust  valve  is  opened  and  so  continues  during  the 
return  stroke,  while  the  steam  pressure  is  being  exerted  on  the 
opposite  face  of  the  piston,  until  the  pressure  on  that  side  of  the 
piston  is  reduced  to  3  pounds,  absolute. 

The  second  diagram,  an  actual  tracing  from  the  intermediate 
cylinder  of  a  triple  expansion  engine,  gives  a  good  idea  of  the 
appearance  of  an  average  card  for  a  double-acting  cylinder.  As 
will  be  seen,  the  figure  is  nearly  duplicated  in  reversed  position. 


__Q 

JjQ. 
7*7 


V 


x 


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ss 


VAeULI/m      LJNA 


FIG.  388.  —The  Cycle  of  a  Steam  Engine,  as  shown  by  the  Indicator  Card.  On  this  tracing, 
the  admission  is  shown  from  A  to  C;  the  cut-off  at  C;  the  expansion  curve  from  C  to 
R;  the  release,  or  opening  of  the  exhaust,  at  R,  exhaust  continuing  from  R  to  B;  clos- 
ing of  the  exhaust  valve  at  B;  compression  of  the  residual  steam  in  the  cylinder  clear- 
ance, from  B  to  A.  The  figures  on  the  left-hand  vertical  line  indicate  the  gauge  press- 
ures. This  diagram  shows  the  operative  conditions  in  a  "  high-pressure  "  cylinder; 
Fig.  232,  in  a  "  low-pressure  "  cylinder. 

It  would  be  identical  if  the  cycular  conditions  were  perfect,  and 
if  the  valve  were  perfectly  adjusted. 

Reading  an  Indicator  Diagram. — The  simplest  method  of 
reading  a  diagram  is  to  rule  equidistant  lines  from  the  vertical 
initial  pressure  line,  so  as  to  divide  it  into  ten  equal  parts,  or 
areas.  Ordinates,  indicated  by  the  dotted  lines,  are  then  ruled 
between  these,  and  given  a  value  equivalent  to  the  average  of 
pressure  represented  by  the  lines  on  either  side,  as  indicated  by 
the  point  of  contact  with  the  admission  line  and  the  expansion 
curve.  Thus  in  the  single  "low-pressure"  diagram  the  three 
ordinates  ruled  on  the  admission  line  have  each  a  value  of  77 
pounds,  which  represents  80  pounds  less  3,  back  pressure.  The 


STEAM  AND   ITS  USE. 


535 


fourth,  touching  the  expansion  curve  at  the  point  of  57  pounds, 
is  marked  54  pounds;  and  so  on  to  the  tenth  ordinate.  The 
sum  of  the  ordinates  (449  pounds)  divided  by  this  number  (10), 
gives  44.9  pounds  per  square  inch  as  the  mean  effective  pressure 
throughout  the  cycle,  or  the  average  of  efficient  pressure  ex- 
erted on  the  piston,  while  the  actual  pressure  is  undergoing  a 
steady  fall  from  77  pounds  to  18  pounds,  absolute.  In  similar 
fashion  the  diagram  for  both  strokes  is  ruled  off  and  estimated, 
the  figures  at  the  top  of  the  figure  indicating  the  cycle  of  press- 
ure changes  for  the  right-hand  stroke,  those  at  the  bottom  the 
cycle  for  the  left-hand,  or  return,  stroke. 


>M 

o» 

FIG.  389.  —Ideal  Indicator  Card  for  a  low-pressure,  or  condensing,  engine,  showing  the  fall 
of  pressure  below  the  atmospheric  line.  As  shown  in  this  cut,  the  effective  steam 
pressures  at  the  various  points  in  the  cycle  vary  between  a  maximum  of  60  pounds 
and  13.75  pounds  to  the  square  inch  before  the  opening  of  the  exhaust.  The  sum  of 
the  ten  figures  for  pressure  is  347.75,  which,  divided  by  10,  gives  34.775,  as  the  expres- 
sion for  the  mean  effective  pressure.  Because  of  the  use  of  a  condenser  to  reduce  the 
back  pressure,  this  figure  represents  the  actual  effective  working  pressure  less  3 
pounds,  as  indicated  on  the  diagram. 

Pressures  and  Temperatures  of  Steam. — In  order  that  the 
steam-carriage  driver  may  understand  by  a  glance  at  the  gauge 
what  temperature  is  in  his  boiler,  the  following  table  of  ordinary 
pressures  is  given : 

Temperature. 


Pressure.  Temperature. 
15  Ibs.  —  212°  F. 
20  Ibs.  —  228°  F. 
25  Ibs.  —  241°  F. 
30  Ibs.  ~  252°  F. 
35  Ibs.  —  261°  F. 
40  Ibs.  —  268°  F. 
45  Ibs.  —  275°  F. 
50  Ibs.  —  282°  F. 


—  288°  F. 
F. 


Pressure. 
55  Ibs. 

60  Ibs.  —  294' 

65  Ibs.  —  299°  F. 

70  Ibs.  —  304°  F. 

75  Ibs.  —  309°  F. 

80  Ibs.  —  313°  F. 

85  Ibs.  —  316°  F. 

90  Ibs,  —  323°  F. 


Pressure. 
100  Ibs. 
105  Ibs. 
120  Ibs. 
135  Ibs. 


Temperature. 

-  330°  F. 
~  333°  F. 

-  343°  F. 

-  352°  F. 


150  Ibs.  —  362°  F. 
165  Ibs.  —  369°  F. 
180  Ibs.  —  375°  F. 
195  Ibs.  —  383°  F. 


536 


SELF-PROPELLED    VEHICLES. 


Power  Estimates  from  the  Steam  Consumption. — Referring 
to  the  tables  on  the  properties  of  saturated  steam,  given  in  the 
appendix,  we  find  a  means  of  determining  the  power  capacity  of 
the  engine  from  the  diagram.  Thus,  taking  the  initial  pressure 
in  the  cylinder,  77  pounds,  we  find  it  equivalent  to  a  tempera- 
ture of  309.3°,  Fahrenheit  ;  taking  the  final  pressure,  18  pounds, 
we  find  it  equivalent  to  a  temperature  of  222.4°,  Fahrenheit,  and, 
the  mean  effective  pressure,  44.9  pounds,  to  about  274°.  This 
temperature  represents  about  1197.4  heat  units  per  pound  of 
water,  which  is  equivalent  to  924,392.8  foot-pounds;  estimating 
772  foot-pounds  per  thermal  unit.  Therefore,  a  cylinder,  such 


FIG.  390.— Card  from  the  intermediate  pressure  cylinder  of  a  triple  expansion  engine, 
with  figures  for  pressure  at  the  various  points  in  the  cycle.  This  is  an  average  good 
diagram  for  a  double-acting  cylinder.  The  mean  effective  pressure  is  found,  as  fol- 
lows: 151.70  + 162  =  313.70.  Divide  this  by  20,  we  have  15.685  Ibs.  =  M.  E.  P. 

as  is  mentioned  in  the  quotation  from  Forney,  which  can  con- 
tain one-tenth  pound  of  steam  per  stroke  at  a  mean  pressure  of, 
say  44.9  pounds,  as  per  above  diagram,  will  develop  at  200 
revolutions,  or  400  strokes,  per  minute,  a  horse-power  shown  by 
the  following  formula : 

92439.28X400 


33,000 


=  1120.48. 


Elements  in  Estimates  on  Horse-Power. — As  a  moment's 
reflection  will  readily  reveal,  the  elements  entering  into  the  es- 
timate of  an  engine's  horse-power  are  the  effective  temperature 


STEAM  AND   ITS  USE.  537 

of  the  steam,  as  indicated  by  the  mean  pressure  throughout  the 
stroke;  the  content  of  the  cylinder,  as  indicated  by  the  length 
of  the  stroke  and  the  area  of  the  piston ;  and  the  number  of  revo- 
lutions per  minute.  The  product  found  by  multiplying  these 
factors  will  give  the  number  of  foot-pounds  made  available; 
which  expression,  divided  by  33,000,  gives  the  indicated  horse- 
power. 

The  denominator,  33,000,  expresses  the  number  of  foot- 
pounds per  minute  in  a  horse-power.  Thus,  a  horse-power  is 
such  a  force  as  can  lift  a  weight  of  one  pound  through  550  feet 
in  each  second,  or,  such  as  can  lift  a  weight  of  550  pounds 
through  one  foot  in  each  second.  This  force  constantly  exerted 
through  one  minute,  or  sixty  seconds,  can  lift  33,000  pounds 
through  one  foot,  or  one  pound  through  33,000  feet.  Since, 
however,  the  action  involves  motion,  it  is  cumulative  in  both 
time  and  space ;  requiring  an  increased  area  of  operating  surface, 
or  an  increased  length  of  time,  or  both,  to  accomplish  work  in 
excess  of  the  figures  given.  Thus,  an  engine  exerting  pre- 
cisely one  effective  horse-power  can  raise  10  pounds  through 
only  3,300  feet  per  minute,  or  55  feet  per  second,  and  requires 
10  minutes  or  600  seconds,  to  raise  330,000  pounds  through  the 
vertical  distance  of  one  foot.  To  so  enlarge  the  capacity  of  an 
engine  that  it  can  do  ten  times  the  indicated  amount  of  work 
in  a  given  space  of  time,  or,  so  that  it  can  do  the  indicated 
amount  of  work  in  one-tenth  that  given  time,  involves  that  the 
cubic  content  of  its  operating  chamber,  or  cylinder,  be  propor- 
tionally increased,  in  order  that  ten  times  the  amount  of  steam 
may  be  utilized  in  a  given  time,  or  for  the  accomplishment  of  a 
given  work  at  each  stroke  of  the  piston.  For  it  is  evident  that  a 
mean  effective  pressure  of  45  pounds  per  square  inch  means  90 
pounds  available  pressure  with  a  piston  area  of  two  square 
inches;  180  pounds  available  pressure  with  a  piston  area  of  four 
square  inches,  and  22.5  pounds  available  pressure  with  a  piston 
area  of  1-2  square  inch. 

First  Rule  for  Calculating  Horse-Power — On  the  basis  of 
these  evident  principles,  two  simple  rules  may  be  derived  for 
calculating  the  indicated  horse-power.  This,  however,  is  always 
in  excess  of  the  actual  efficient  horse-power,  as  will  be  subse- 
quently explained.  While  there  are  numerous  formulae  for 


538  SELF-PROPELLED    VEHICLES. 

determining    this    point,    one    of    the    most     familiar    is    as 
follows : 

(a)  Find  the  area  of  the  piston  by  multiplying  the  square  of  a 
radius  in  inches  by  3.14159  (ratio  between  circumference  and 
diameter). 

(b)  Find  the  pressure  in  pounds  on  the  piston  by  multiplying 
the  area  by  the  mean  pressure  per  square  inch. 

(c)  Find  the  length  in  feet  traveled  by  the  piston  per  minute, 
by  multiplying  the  length  of  the  stroke  in  feet,  or  fractions  of  a 
foot,  by  twice  the  number  of  ascertained  revolutions  of  the  crank 
shaft  per  minute.     This  equals  the  number  of  strokes  per  minute 
for  a  double-acting  cylinder. 

(d)  Find  the  foot-pounds  available  during  the  given  space  of 
time  (one  minute)  by  multiplying  the  pressure,  in  pounds,  by  the 
length  traveled  by  the  piston,  in  feet. 

(e)  Find  the  I.  H.  P.  (indicated  horse-power)  by  dividing  this 
last  product  by  33,000. 

The  formula  is :        PLAN 
33,000 

P  being  equivalent  to  the  M.E.P.  (mean  effective  pressure)  in 
pounds  per  square  inch. 

L  being  equivalent  to  the  length  of  the  stroke  in  terms  of  feet. 

A  being  equivalent  to  the  area  of  the  piston  in  square  inches. 

N  being  equivalent  to  the  number  of  strokes  of  the  piston,  or 
twice  the  number  of  revolutions  of  the  crank-shaft,  per  minute. 

The  element  of  speed,  as  expressed  in  terms  of  strokes,  or 
revolutions,  per  minute,  is  important,  and  fundamental,  in  es- 
timates on  power,  since,  as  must  be  evident  from  what  has  al- 
ready been  said,  the  superior  power-capacity  of  one  engine  over 
another  consists  principally  in  being  able  to  do,  for  example, 
ten  times  the  work  in  a  given  time,  or  to  do  the  same  work  ten 
times  as  fast.  Therefore,  an  engine  that  can  propel  a  given  mass 
and  weight  of  machinery  at  300  revolutions  of  its  crank-shaft 
and  fly-wheel,  per  minute,  is  evidently  three  times  more  power- 
ful than  another  engine  which  can  move  the  same  mass  and 
weight  of  machinery  at  only  100  revolutions  per  minute.  Con- 
sequently, in  forming  the  expression  for  the  horse-power  ratio 
of  any  given  engine,  the  other  essential  factors  of  the  numera- 
tor are  to  be  increased,  as  the  number  of  times  per  minute  the 
engine  performs  its  complete  cycle. 


STEAM  AND   ITS  USE.  539 

The  flean  Effective  Pressure. — The  mean  effective  pressure 
(M.E.P.)  may  be  calculated  from  the  indicator  diagram,  as 
above  explained,  but  it  may  also  be  found  by  knowing  the  initial 
steam  pressure  in  the  cylinder  and  the  point  of  cut-off.  Thus, 
as  given  in  the  table,  entitled,  "To  find  the  M:  E.  P.  of  a  Steam 
Engine,"  included  in  the  appendix,  we  may  take  any  initial 
pressure  given  in  the  first  column,  and  follow  the  horizontal  dis- 
tance to  the  column  corresponding  to  the  number  of  times  the 
steam  is  expanded.  Thus  if  the  initial  pressure  be  150  pounds, 
and  the  steam  be  expanded  five  times,  we  have  a  mean  effective 
pressure  of  78.30  pounds  absolute,  which,  if  the  engine  ex- 
hausts to  atmosphere,  must  be  diminished  by  15,  representing 
the  back-pressure,  giving  63.30. 

To  apply  the  formula  given  above  to  the  calculation  of  an  en- 
gine of,  say,  three  inches  piston  diameter ;  four  inches  stroke ; 
63.3  mean  effective  pressure,  and  200  revolutions  per  minute,  we 
have : 

63.3 X. 333x7.0686x400  _.  j  80  j   H   p 
33,000 

In  this  expression  63.3  represents  the  M.E.P.  calculated  as 
above ;  .333,  the  fractional  expression  in  terms  of  one  foot  for 
four  inches ;  7.0686,  the  area  of  a  circle  whose  diameter  is  three 
inches ;  and  400,  the  number  of  strokes  per  minute  for  a  double 
acting  cylinder  at  200  revolutions  of  the  crank-shaft..  The  result 
is,  approximately,  two  horse-power,  which,  multiplied  by  2  to 
represent  the  two  cylinders,  as  in  most  steam  carriage  engines, 
gives  an  indicated  horse-power  of  about  four,  which  is  fairly 
representative. 

Second  Rule  for  Calculating  Horse- Power — A  second  rule 
for  computing  the  horse-power  of  a  steam  engine  gives  the  prod- 
uct of : 

(a)  The  square  of  the  piston  diameter. 

(b)  The  length  of  the  stroke  in  feet. 

(c)  The  number  of  strokes  per  minute. 

(d)  The  M.  E.  P.  per  square  inch. 

(e)  The  constant,  .0000238. 

Computing  for  the  engine  mentioned  above,  we  have : 

9  X  .333  X  400  X  63.3  X  .0000238  =  1.80+. 


CHAPTER    THIRTY-THREE. 
CONSTRUCTION   AND   OPERATION   OF  A   STEAM   ENGINE. 

The  Slide  Valves  of  a  Steam  Cylinder — The  mechanism  by 
which  steam  is  admitted  to  the  cylinder  of  a  steam  engine,  con- 
sists of  a  sliding  valve  of  such  a  shape  as  to  open  communication 
from  one  end  of  the  cylinder  to  the  exhaust,  while  the  other  end 
of  the  cylinder  is  receiving  steam  direct  from  the  steam  chest. 
This  will  be  readily  understood  from  the  accompanying  illus- 
tration. There  are  two  kinds  of  valves  in  common  use  on  steam 
carriage  engines ;  the  common  D-valve  shown  herewith,  and  the 
piston  valve,  as  shown  in  a  number  of  engines  hereafter  to  be 
described.  The  object  obtained  by  both  valves  is  the  same,  al- 
though the  piston  valve  is  preferred  by  many  engineers  because 
it  is  better  balanced  in  its  operation,  and  also  because,  owing 


FIG.  391.— Slide  Valve  of  a  Steam  Engine,  showing  position  after  cut-off  of  steam  from 
right-hand  end  of  cylinder,  the  exhaust  continuing  full  from  the  left-hand  end. 

to  its  packing  rings,  it  is  less  liable  to  leakage.  However,  with  a 
well-made  valve  of  either  variety,  the  ends  of  economy  and 
durability  are  equally  maintained. 

The  Piston  of  a  Steam  Engine — The  piston  of  a  steam  engine, 
as  shown  in  an  accompanying  figure,  usually  consists  of  a  flat- 
tened cylindrical  piece  of  slightly  smaller  diameter  than  the  bore 
of  the  cylinder,  in  which  it  slides.  Steam-tight  contact  is  ob- 
tained by  springing  packing  rings  into  grooves  cut  in  its  cir- 
cumference. The  accompanying  cut  shows  three  such  rings 
sprung  on  the-  piston.  The  steam  admitted  through  the  inlet 
valve  bears  upon  one  face  of  the  piston,  and  by  its  expansive 
energy  causes  the  piston  to  move.  As  may  be  understood, 

540 


THE  STEAM  ENGINE.  541 

however,  from  the  fact  that  the  piston  rod  is  attached  to  one  face 
of  the  piston,  the  bearing  surface  of  the  steam  is  decreased  as 
the  area  of  the  rod.  This  item  must  be  considered  in  exact  cal- 
culations on  engine  horse-power,  although  for  ordinary  pur- 
poses it  is  negligible. 

The  Operation  of  the  Slide  Valve. — The  valve  controlling  the 
inlet  and  exhaust  ports  of  a  steam  cylinder  is  made  of  such 
length  that,  when  in  mid-position,  it  completely  closes  both 
inlet  ports,  neither  admitting  steam  nor  allowing  it  to  be 
exhausted.  In  the  valve  shown  on  the  accompanying  sec- 
tional cut,  it  is  evident  that,  supposing  it  to  be  moved 
either  to  the  right  or  to  the  left,  the  communication  will  be 
opened  with  the  exhaust  port  on  the  one  side,  sooner  than  with 
the  steam  chest  on  the  other,  thus  permitting  with  a  very  slight 


FIG.  392.  -The  Piston  of  a  small  double-acting  steam  engine,  showing  method  of  connect 
ing  the  piston  rod,  and  the  position  of  the  packing  rings.  The  parts  are:  a,  a,  the 
body  of  the  piston;  6,  b,  the  circumference  bearing  the  packing  rings;  c,  c,  the  cen- 
tral boss  receiving  the  coned  end  of  the  rod. 

variation  in  the  length  of  the  stroke,  that  the  exhaust  remain 
open  even  while  the  inlet  of  the  steam  to  the  opposite  face  of  the 
piston  is  cut  off.  In  calculating  the  operation  of  cylinder  valves 
there  are  two  important  items  to  be  considered — the  "lap"  and 
the  "lead"  of  the  valves.  The  "lead"  of  a  valve  is  the  amount 
by  which  the  steam  port  is  open  when  the  piston  is  at  the  begin- 
ning of  the  stroke.  According  as  this  is  more  or  less  the  inlet 
of  steam  is  varied  through  the  several  fractions  of  the  stroke. 
The  lead  may  be  changed  either  by  cutting  down  the  lap  of  the 
valve,  or  by  varying  the  stroke  length  of  the  valve  and  its  rod. 


542 


SELF-PROPELLED    VEHICLES. 


The  "lap"  of  a  valve  indicates  any  portion  added  to  the  length 
of  the  valve,  so  as  to  increase  the  portion  of  the  stroke  during 
which  the  ports  are  covered,  beyond  that  length  which  is  posi- 
tively required  to  insure  the  closing  of  all  ports  when  the  valve 
is  in  mid-position.  There  are  two  kinds  of  "lap."  The  "outside 
lap"  is  any  portion  added  to  the  length  of  the  valve  beyond  that 
necessary  to  cover  both  inlet  ports  at  mid-position.  The  "in- 
side lap"  is  any  portion  added  to  the  hollow  or  inside  portion  of 
the  D-valve,  over  and  above  what  is  necessary  in  order  to  cover 
the  inner  edges  of  the  steam  ports,  and  to  close  the  exhaust  port 
from  both  sides  when  the  valve  is  in  mid-position. 


FIG.  393.— Diagrams  illustrating  the  "  Lap"  and  "  Lead  "  of  a  Steam  Cylinder  Slide  Valve. 
In  both  sections,  S  and  S  are  the  steam  ports,  and  D  the  exhaust.  The  upper  section 
illustrates  the  "laps"  of  a  valve;  the  space  between  the  lines  C  and  X  giving  the 
"outside  lap,"  and  between  the  lines  X  and  1  the  "  inside  lap"  The  lower  section 
illustrates  the  ''lead  "  of  a  valve;  the  space  between  lines  B  and  Y  showing  the  open- 
ing of  the  valve  at  the  beginning  of  the  right-hand  stroke. 

As  already  suggested  in  the  previous  chapter,  the  exhaust 
valve  is  closed  somewhat  before  the  completion  of  the  stroke, 
thus  allowing  the  residual  steam  in  the  clearance  to  be  com- 
pressed somewhat  before  the  opening  of  the  inlet.  The  most 
important  result  obtained  in  this  manner  is  that  the  compression 
produces  a  temperature,  as  near  as  possible,  the  same  as  that 
of  the  incoming  steam,  which  is  an  efficient  factor  in  heat 
economy,  although  producing  some  back  pressure  that  slightly 
reduces  the  M.  E.  P.  Another  important  consideration  is  that 
a  soft  cushion  is  thus  provided  for  the  forward-moving  piston, 


THE  STEAM  ENGINE. 


543 


which  acts  to.  save  unnecessary  wear  on  the  crank  and  other  mov- 
ing parts,  as  is  most  essential  in  a  small  engine. 

From  the  operations  of  this  valve  and  cylinder,  it  must  be 
evident  that  its  stroke  cannot  be  equal  to  that  of  the  piston  in 
the  main  cylinder.  It  cannot,  therefore,  be  operated  direct  from 
the  crank-shaft  of  the  engine.  Accordingly,  the  most  usual 
method  of  operating  the  steam  valves  of  an  engine  is  by  an 
eccentric  on  the  main  shaft,  which  operates  the  valve  rod.  This 
device  may  be  either  a  single  or  double  eccentric,  according  to 
the  requirements,  but  when  ready  reversal  of  the  engine's  mo- 
tion is  desired,  as  in  the  case  of  a  locomotive  or  marine  engine, 
the  double  eccentric  with  the  shifting,  or  Stephenson,  link  is  most 
generally  used. 


FIG.  394.— Section  through  a  Steam  Cylinder  and  Valve  Chest,  showing  parts.    A  is  the 
cylinder;  B,  the  steam  chest;  C  and  C,  the  cylinder  heads;  D,  the  stuffing  box;  a  and 


a,  the  packing  gland;  c,  the  piston  rod;  E,  the  exhaust  port;  S  and  S,  the  steam  ports; 
V,  the  slide  valve;  e,  e,  the  packing  gland, " 


held  in  place  by  screws  in  this  engine. 


The  Eccentric  Gear  and  Link  fiction. — Ah  eccentric  is 
a  circular  piece  of  metal,  a  wheel  in  fact,  except  for  the  fact  that 
instead  of  turning  upon  its  centre,  it  is  attached  to  the  shaft  at 
a  point  near  its  periphery.  Around  this  disc-shaped  piece  is 
attached  a  circular  metal  strap,  joined  to  a  rod,  which  may  be 
either  attached  direct  to  the  valve  rod,  or,  where  two  eccentrics 
are  used,  to  one  end  of  the  swinging  link.  The  link  is  an  arc- 
shaped  metal  piece,  usually  made  with  a  slot  through  the  greater 
part  of  its  length.  It  is  hung  from  its  centre  point  to  a  link- 
saddle,  which,  as  shown  in  the  accompanying  figure,  is  bolted 
to  either  side  of  the  slot  and  is  suspended  from  the  link-hanger 


544 


SELF-PROPELLED    VEHICLES. 


either  above  or  below.  Within  the  slot  is  set  a  link-block,  as 
it  is  called,  so  that  it  may  slide  in  the  slot  through  its  entire 
length,  whenever  the  link  is  raised  or  lowered  on  its  hanger. 
To  this  link-block  is  attached  the  valve  rod.  The  general  ar- 
rangements of  the  link  motion  may  be  understood  from  the 
accompanying  illustration. 

The  Operation  of  the  Shifting  Link.— As  already  stated, 
the  link  motion  was  originally  intended  only  for  reversing  the 
engine,  which  is  to  say  to  enable  the  steam  to  be  cut  off  from 


FIG.  395.  —Diagram  of  the  Link  Motion  and  Eccentric  Gear  of  a  Steam  Engine.  The  parts 
shown  are:  (1)  backward  eccentric;  (2)  forward  eccentric:  (3-4)  eccentric  rods:  (5) 
slotted  shifting  link;  (6)  link  hanger;  (7)  reversing  arm;  (8)  link  saddle  pin;  (9)  link 
block;  (10)  valve  stem;  (11)  reach  rod.  The  position  shown  in  the  cut  indicates  that 
the  backward  eccentric  is  in  gear  which  gives  a  reverse  motion  to  the  engine. 

one  side  of  the  cylinder  and  admitted  to  the  other,  whenever  de- 
sired, by  shifting  the  motion  of  the  slide-valve.  In  addition  to 
this  function,  however,  the  link  motion  provides  a  means  for 
using  the  steam  expansively,  when  cutting  off  the  supply  of  live 
steam  at  any  earlier  point  in  the  piston  stroke,  which  act  is  ac- 
complished by  reducing  the  travel  of  the  slide-valve.  When 
the  link-block  is  at  one  end  of  the  slot,  the  valve  receives  the 
motion  of  the  eccentric  rod  attached  to  that  end  of  the  link,  and, 
consequently,  since  the  links  are  set  at  angles  somewhat  greater 
than  1 80  degrees,  the  one  is  for  the  forward  motion  of  the  en- 


THE  STEAM  ENGINE. 


545 


gine,  the  other  for  the  reversed  motion.  In  the  accompanying 
illustration,  the  backward  eccentric  is  in  gear.  'By  this  means, 
whenever  the  link  is  shifted,  only  the  eccentric  whose  rod  stands 
opposite  the  link-block  imparts  its  motion  to  the  valve.  The 
other  is  practically  inactive,  except  for  imparting  a  slight  oscil- 
latory motion  to  the  link,  which  in  general  practice  is  negligible. 
The  link  which  is  in  gear  acts,  in  reality,  like  a  short-throw 
crank,  or  as  if  it  were  a  single  eccentric.  From  the  position  of 
"full-gear" — that  is,  when  the  link-block  stands  at  either  end  of 
the  slot — the  travel  of  the  valve  may  be  more  or  less  modified 
until  the  centre  point  of  the  slot  is  reached,  which  point  is  called 


FIG.  396.  —Diagram  of  the  Operation  of  the  Link  Motion.  The  centres  of  the  two  eccen- 
trics being  at  4  and  8,  the  crank  pin  at  2,  the  link  at  mid-gear,  the  eccentric  rods 
will  be  indicated  by  the  full  lines,  4-6,  8-10.  When  the  crank  pin  is  at  1,  the  centres 
of  the  eccentrics  will  be  at  3  and  7,  and  the  positions  of  the  rods  on  the  dotted  lines, 
3-5  and  7-9.  The  distance,  D,  indicates  the  vertical  distance  between  the  centres  of 
the  eccentrics  in  the  full  and  dotted-line  positions.  If  from  the  centre,  8,  with  the 
rod  as  the  radius,  an  arc  be  drawn  to  F,  the  distance,  C,  shows  the  position  of  the  link 
if  both  rods  were  '•  open  "  with  the  crank  at  the  cylinder  end,  2,  instead  of  at  the  op- 
posite dead  centre,  1.  The  distance,  C,  is  equal  to  the  distance,  E,  and  the  total  dis- 
tance (D  +  E)  that  the  valve  moves  is  twice  the  lap,  plus  twice  the  lead,  plus  the 
distance,  or  angularity,  occasioned  by  the  rods  being  crossed,  when  the  crank  is  on 
the  cylinder  end  dead  centre,  2,  becoming  opened  when  the  crank  is  at  dead  centre,  1. 

mid-gear.  There  the  travel  in  either  direction  is  so  slight  that 
the  steam  and  exhaust  ports  of  the  cylinder  are  not  opened.  This 
is  in  reality  the  "dead  point/'  and  further  shifting  of  the  link 
in  the  same  direction  begins  the  process  of  reversing  by  increas- 
ing the  travel  of  the  valve  in  the  opposite  direction.  When  at 
mid-gear  the  valve  partakes  of  the  motion  of  both  eccentrics 
equally,  but  since  their  motion  describes  a  cassinian,  or  flattened 
figure  8,  laid  on  its  side,  of  which  the  link-block  is  the  centre,  the 
motion  is  at  its  point.  Although  this  general  movement  is  con- 
tinued so  long  as  the  engine  is  in  operation,  it  is  reduced  to  prac- 
tical zero  at  the  link-block  set  at  full  gear. 


SELF-PROPELLED    VEHICLES. 


When  the  link  is  at  full  gear,  the  travel  of  the  valve  is  equal 
to  twice  the  throw  of  the  eccentric,  less  the  angularity  of  the 
eccentric  rod.  When  the  link  is  at  mid-gear,  the  travel  of  the 
valve  is  equal  to  twice  the  lap  and  lead  of  the  valve,  plus  twice 
the  angularity  of  the  eccentric  rods.  By  the  angularity  of  the 


1 


Open   Rods 


Grossed    Pods 


FIG.  397.— Diagram  showing  the  positions  of  the  eccentric  throws  and  rods  at  full  gear 
and  mid-gear,  when  the  rods  are  "open"  and  "crossed"  with  the  crank  at  the  for- 
ward dead  centre,  marked  1  in  the  previous  cut. 

eccentric  rods  is  meant  the  distance  the  centre  of  the  link  or  the 
valve  would  move,  should  the  rod  of  the  geared  eccentric  be 
disconnected  from  it  and  connected  with  the  other  link.  The 
amount  of  the  angularity  thus,  of  course,  varies  with  the  length 
of  the  rods.  The  shorter  the  rods,  the  greater  the  travel  of  the 


THE  STEAM  ENGINE.  547 

valve,  owing  to  the  crossing  of  the  rods  during  a  one-half  revo- 
lution of  the  crank.  When  the  eccentric  rods  of  a  direct  con- 
nected link  motion  are  disposed  as  shown  in  the  accompanying 
diagram,  and  the  link  motion  and  gear  of  the  crank  is  at  the 
dead  point  marked  I,  the  rods  are  said  to  be  open.  If  they  are 
disposed  as  shown  by  the  dotted  lines  in  the  same  figure,  and 
the  crank  is  at  the  dead  point,  2,  they  are  said  to  be  crossed. 
There  is,  however,  an  important  difference  in  the  operation  in- 
volved in  the  relative  positions  of  the  rods  to  the  crank,  as  shown 
by  the  travel  of  the  steam  valve,  since  rods  which  are  open  at 
the  specified  point  give  an  increasing  lead  from  full-gear  towards 
mid-gear,  while  rods  crossed  at  that  point  give  a  decreasing 
lead  in  the  same  direction.  Variation  of  lead  from  full-gear 


FIG.  398.  — Diagram  with  a  single  eccentric,  illustrating  the  position  of  the  steam  valve, 
when  the  crank  pin  is  at  the  forward  dead  centre,  the  throw  of  the  eccentric  being 
at  an  angle  off  the  perpendicular.  The  arrows  show  the  direction  of  motion. 

to  mid-gear  is  due  to  the  curvature  of  the  link-arc,  and  for  a 
link  of  short  radius  is  more  pronounced  than  for  .a  link  of  longer 
radius.  As  a  general  rule,  the  radius  of  the  link  is  equal  to  the 
length  of  the  eccentric  rod. 

The  Practical  Expansion  Ratio  for  Steam. — In  the  practical 
operation  of  the  steam  engine,  as  most  generally  understood, 
the  steam  is  fed  direct  from  the  boiler  to  the  cylinder,  there  ex- 
panding from  its  original  pressure  to  a  number  of  volumes,  pro- 
portioned to  the  length  of  the  stroke  and  point  of  cut-off.  The 
idea  of  cutting  off  the  supply  of  steam  before  the  completion  of 
the  stroke,  and  making  use  of  its  expansive  energy  during  the 
remaining  portion,  constitutes,  as  we  have  seen,  the  first  im- 
provement made  by  Watt.  According  to  Boyle's  Law,  already 
quoted,  the  pressure  of  the  steam  is  in  exactly  inverse  ratio  to 


548 


SELF-PROPELLED    VEHICLES. 


its  expansion,  which  is  to  say  that  when  a  body  of  steam  is  ex- 
panded to  twice  its  original  volume,  it  should  have  just  one-half 
its  original  pressure,  so  long  as  the  temperature  be  constant. 
This  law  is  never  exactly  followed  in  practice,  the  general  rule, 
as  shown  by  indicator  diagrams,  being  a  rapid  fall  during  the 
first  period  of  expansion  and  a  more  gradual  one  in  the  latter 


FIG.  399.  —Diagram  of  a  "  Cross  Compound  "  Steam  Engine.  The  cranks,  C  and  C,  are  at 
90°.  The  high-pressure  steam  port  is  at  S;  the  H.  P.  exhaust  to  L.  P.  cylinder  at  R, 
and  the  exhaust  to  atmosphere  from  the  low-pressure  cylinder,  at  E. 

period.  However,  for  general  purposes,  the  law  is  assumed  to 
be  perfectly  operative,  and  the  rule  for  calculating  the  pressure 
at  any  point  of  expansion,  is  to  divide  the  original  absolute  pres- 
sure by  the  number  of  times  it  has  expanded.  Thus,  steam  fed 
to  a  cylinder  at  100  pounds  gauge,  or  115  pounds  absolute,  has 
a  pressure  of  57^  pounds  when  expanded  to  two  volumes,  a 
pressure  of  38  1-3  pounds  when  expanded  to  three  volumes  and 
a  pressure  of  28|  pounds  when  expanded  to  four  volumes.  It 
would,  therefore,  require  as  many  expansions  to  reduce  the 
gauge  pressure  of  100  pounds  to  atmosphere,  as  15  is  contained 
in  115,  which  is  7  2-3  times.  If  the  flow  of  steam  to  the  cylinder 
be  cut  off  at  one-half  stroke,  it  has  been  ascertained  by  nu- 
merous experiments,  that  its  efficiency  will  be  increased  i  1-7 


THE  STEAM  ENGINE.  549' 

times  what  it  would  have  been  if  the  steam  at  the  same  point 
has  been  released  into  atmosphere.  The  following  %table  gives  the 
efficiency  of  steam  cut  off  at  various  other  points  of  the  stroke : 

Cutting  off  at  yV  stroke  'increases  efficiency  3.3  times. 
"        i         "              "  "     "    3-0       " 

"        T2T>          "  "  "  2.6        " 

..         £  <,  «  ,<  2>39      „ 

"        A          "  "  2.2         *« 

»          |  "  "  ««  .98       " 

„         T4_          ,',  „  „  82       „ 

"          ±  "  "  "  .69       " 

"        A  "  "  "  .50       " 

•47     " 

"      iV        "  "  -35     " 

"       |         "  "  "  .28     " 

These  figures  give  a  general  idea  of  the  economy  gained  by 
the  practice  of  cutting  off  the  steam  at  various  points  of  the 
stroke,  but,  as  is  evident,  the  end  of  economy  is  obtained  by 
altering  the  final  pressure  in  the  cylinder,  and,  consequently,  also 
the  mean  effective  pressure  throughout  the  entire  cycle.  If, 
therefore,  we  wish  to  utilize  the  full  power  of  any  given  boiler 
pressure,  the  end  of  combined  economy  and  high  efficiency  is  far 
better  attained  by  the  operation  known  as  compounding. 

Limits   of   Varying  the  Valve   fiction   by  the  Link. — On 

the  question  of  the  practical  limits  of  varying  the  cut-off  of  the 
valve,  by  varying  the  motion  on  the  link,  authorities  seem  to 
vary  in  regard  to  the  steam  engines  used  on  carriages.  Several 
manufacturers,  however,  use  a  notched  quadrant  for  enabling 
the  driver  to  shift  the  link,  as  desired,  and  with  apparently  good 
results,  in  spite  of  the  oft-repeated  claim  that  the  engine  of  a 
steam  carriage  is  too  small  to  allow  of  a  very  wide  variation  in 
this  respect.  On  the  authority  of  one  or  two  practical  steam- 
carriage  drivers,  whose  opinions  have  appeared  in  print,  it  may 
be  stated  that  some  advantage  in  point  of  steam  economy  has 
been  achieved  by  varying  the  cut-off  from,  say,  seven-eighths 
to  one-half  stroke  on  a  level  roadway.  The  majority  opinion 
has  it,  however,  that,  although  some  saving  may  be  achieved 
in  this  direction,  proper  care  and  management  of  the  motor  and 
parts  attain  the  end  far  more  effectively:  since  the  strain  on 
the  driving  mechanism  incident  to  shifting  the  link 


550  SELF-PROPELLED    VEHICLES. 

increases  wear  and  tear  in  an  even  greater  proportion  than 
the  gain  in  steam  saving.  In  short,  the  situation  seems  to  be 
that  a  small  steam  motor  requires  a  fly  wheel  to  compensate  for 
the  jar  resulting  from  frequent  shifting  of  the  steam  inlet. 

On  Compounding  a  Steam  Engine. — A  compound  engine 
is  one  in  which  the  steam  is  used  several  times  over  in  as  many 
separate  cylinders,  although  usually  applied  to  engines  operating 
with  two  cylinders.  The  steam  is  fed  from  the  boiler  direct  to 
the  first  cylinder,  in  which  it  is  cut  off  late  in  stroke,  in  order  that 
its  pressure  may  be  utilized  to  the  greatest  possible  extent  The 
exhaust  from  this  cylinder  is  then  fed  into  the  second  cylinder, 
generally  two  or  three  times  the  cubic  contents  of  the  first,  and 
is  worked  expansively  to  a  point  as  near  atmospheric  pressure 
as  possible.  The  most  practical  and  efficient  application  of  this 
principle  is  in  the  triple  and  quadruple  expansion  engines,  so 
largely  used  in  marine  work,  which,  in  connection  with  the 
vacuum-producing  condenser,  allows  the  steam  to  be  worked 
from  the  highest  available  pressure  down  to  practical  zero. 
There  are  two  common  forms  of  compound  engines  of  two  or 
three  cylinders,  which  from  the  arrangements  of  the  working 
parts,  are  known  as  "tandem-compound"  and  cross-compound." 
In  the  tandem-compound  engine,  the  cylinders  are  placed  end 
to  end,  the  several  pistons  operating  one  piston  rod.  In  the 
cross-compound  engine  the  cylinders  are  placed  side  by  side, 
the  two  or  more  piston  rods  operating  on  a  single  crank-shaft. 
The  latter  model  is  that  most  frequently  used  in  compounding 
steam  engines  for  motor  vehicles. 


CHAPTER   THIRTY  FOUR 
SMALL   SHELL  AND   FLUE  BOILERS   FOR   STEAM   CARRIAGES. 

Small  Shell  Boilers  for  Carriages. — Many  of  the  best  known 
makes  of  American  steam  carriage  have  vertical  fire-tube  shell 
boilers,  usually  placed  beneath  the  seat.  All  such  boilers  are  of 
small  dimensions,  frequently  little  over  one  foot  in  either  diam- 
eter or  height,  with  a  consequently  small  water  capacity.  But 
they  have  a  very  extensive  heating  surface,  owing  to  the  inser- 
tion of  a  large  number  of  fire  flues,  and,  according  to  many  show- 
ings, seem  capable  of  generating  a  power  pressure  far  in  excess 
of  the  usual  rule  of  proportions  for  surface.  The  shells  of  such 
small  boilers  are  usually  of  steel,  sheet-riveted  or  cold  drawn 
piping,  with  a  thickness  ranging  between  three-sixteenths  inch 
(as  given  for  the  Marlboro  and  Victor  steam  carriages)  and  five- 
sixteenths  inch  (as  given  for  the  Foster  steam  wagon).  Such 
boilers  admit  a  working  pressure  of  between  150  and  180  pounds 
to  the  square  inch,  with  blow-off  pressure  between  225  and  320 
pounds,  several  of  them  claiming  to  have  withstood  tests  of  more 
than  three  times  their  blow-off  pressure.  The  flues  of  such  small 
boilers,  which  are  generally  of  copper,  about  one-half  inch  in 
diameter  and  16  B.  W.  G.,  or  .065  inch  thick,  are  expanded  into 
the  tube  plates  at  either  end,  the  joints  being  secured  as  strongly 
as  possible. 

Heating:  Surface  of  Small  Boilers. —  The  immense  heating 
surface  afforded  by  using  a  large  number  of  such  flues  in  a  boiler 
of  moderate  dimensions  may  be  illustrated  by  the  following 
figures : 

In  the  ordinary  two  and  four-seat  carriages  made  by  the  Lo- 
comobile Company  of  America  a  boiler  is  used  whose  dimensions 
are  14  x  14  inches,  with  298  half-inch  copper  tubes. 

Computing  for  the  area  of  a  circle  of  14-inch  diameter  we 
find  it  to  represent  153.94  square  inches,  which  gives  307.88 
square  inches  as  the  surface  of  both  tube  plates. 

Computing  for  the  cylindrical  surface  of  the  shell,  we  find  the 

551 


552 


SELF-PROPELLED    VEHICLES. 


circumference  to  be  the  product  of  14  (diameter)  and  3.14159 
(ratio  between  circumference  and  diameter  of  a  circle),  giving 
43.9822  inches  as  the  circumferential  measure,  which,  multiplied 
by  14  (length  of  shell),  gives  615.7506  square  inches,  or  a  total 
surface  for  the  boiler  shell  of  923.63  square  inches,  or  6.39  square 
feet. 

With  the  flue-tubes  we  may  calculate  in  similar  fashion.  Thus 
the  inside  diameter  of  each  tube  is  approximately  one-half  inch, 
exactly  .437  inch.  To  find  the  inside  circumference,  we  multiply 
•437  by  3.14159,  which  gives  us,  in  full,  1.37287483.  Multiplying 
this  by  14,  to  find  the  area  of  each  tube,  we  have  19.22024762 


FIG.  400.— Copper  Shell  and  Flue  Boiler,  with  flange  connections  for  the  tube  plates,  as 
used  on  the  "Locomobile"  and  other  American  steam  carriages.  The  shell  is 
strengthened  by  winding  several  layers  of  steel  piano  wire  around  the  length  of  the 
boiler.  This  cut  gives  a  section  on  the  centre,  showing  one  row  of  flues. 

square  inches,  which  multiplied  by  298  (total  number  of  tubes) 
gives  us  5728.633  square  inches,  or  39.782  square  feet,  as  the 
heating  surface  represented  by  the  flues,  over  six  and  one-half 
times  the  total  outside  surface  of  the  boiler  shell.  If  to  this  figure 
we  add  307.88  square  inches,  or  2.13  square  feet,  the  surface  area 
of  the  two  tube  plates,  we  have  41.91  square  feet,  as  the  total  heat- 
ing surface  of  the  boiler. 

According  to  the  rule  given  above,  a  boiler  of  such  dimensions 
should  be  able  to  drive  an  engine  of  about  three-horse  power. 
But  it  has  been  claimed  that  this  make  of  boiler  has  developed 
over  four-horse  power,  which  fact  is  probably  due  to  rapid  steam 


SMALL  FLUE  BOILERS.  553 

generation  under  fire  from  a  powerful  burner,  and  also  the  effi- 
ciency of  the  engine  used.  Similarly  excellent  results  have  been 
achieved  with  other  makes  of  fire  flue  vehicle  boilers,  a  fact  which 
amply  justifies  the  course  followed  by  most  American  carriage 
builders,  of  adopting  a  steam  generator  of  familiar  pattern  and  in- 
creasing its  efficiency  along  concurrent  lines,  instead  of  spending 
time  and  energy  in  the  effort  to  produce  an  instrument,  which 
should  embody  the  requirements  of  perfection.  - 


FIG.  401.— Small  Carriage  Boiler  made  from  a  seamless  steel  pressing,  the  lower  tube 
plate  being  flanged  over  and  riveted  in,  as  indicated  at  the  base  of  the  figure,  this 
being  the  only  seam  in  the  structure. 

The  Flues  of  Small  Boilers.— Several  carriage  builders  still 
cling  to  the  practice  of  using  steel  tubes  in  their  boilers,  thinking 
by  this  means  to  supply  an  additional  assurance  against  explo- 
sion. The  custom  is  growing,  however,  of  using  cold  drawn  cop- 
per tubes  for  this  purpose,  and  experience  seems  to  warrant  the 
statement  that  boilers  containing  them  are  quite  as  durable  as 
those  constructed  of  steel  throughout.  Copper  is  superior  to  steel 
in  boiler  construction  from  the  fact  that  it  has  a  much  higher 
thermal  conductivity,  involving  considerably  smaller  loss  of  heat 
in  proportion  to  its  exposed  surface;  also  from  the  fact  that  it 


554:  SELF-PROPELLED    VEHICLES. 

more  easily  resists  the  chemical  action  of  impure  water,  in  point 
of  preventing  both  corrosion  and  the  deposit  of  incrustations, 
and  is  less  liable  to  oxidation  from  the  action  of  heat.  On  the 
other  hand,  it  is  inferior  to  steel  in  the  fact  that  its  tensile  strength 
is  greatly  reduced  under  increasing  temperatures.  As  quoted 
by  several  boiler  authorities,  its  diminution  of  strength  increases 
from  .0926  as  compared  to  steel  at  270  degrees,  Fahrenheit,  to 
.2133  at  460  degrees,  .2558  at  532  degrees  and  .3425  at  660  de- 
grees. Well-made  copper  tubes,  however,  can  readily  withstand 


FIG.  402. —Bottom  View  of  a  Type  of  Boiler  shown  in  Fig.  145,  exhibiting  the  method  of 
riveting  in  the  lower  tube  plate. 

a  constant  working  pressure  of  between  150  and  180  pounds  to 
the  square  inch,  which  figures  represent  the  average  used  in 
small  vehicle  boilers.  These  advantages  in  copper,  both  pure 
and  in  alloy,  led  long  since  to  the  use  of  brass  tubes  in  some  lo- 
comotive and  other  large  boilers,  with  the  best  results.  For  this 
purpose  brass  proved  far  superior  to  iron,  or  steel,  in  resisting 
the  abrading  action  of  small  particles  of  coke  or  coal  drawn 
through  the  draught;  in  having  a  greater  power  of  springing 
under  increased  expansion,  and  of  being  less  liable  to  break. 
On  the  other  hand,  if  we  may  deduce  a  principle  from  practical 


SMALL   FLUE  BOILERS.  555 

experience  on  this  point,  the  inferior  strength  of  copper  tubes 
for  boilers  is  a  positive  advantage,  for,  since  they  are  more  liable 
to  collapse  under  stress  of  over-heat  and  expansion,  the  effect 
may  be  similar  to  that  found  in  water-tube  boilers  under  similar 
conditions — the  bursting  of  one  or  two  tubes  instead  of  a  disas- 
trous rending  of  the  outer  shell.  This  seems  to  be  the  experience 
in  some  cases.  A  prominent  steam  carriage  concern  says  of  its 
tubular  boiler :  "If  the  boiler  should  accidentally  be  allowed  to 
run  dry  and  become  overheated,  all  that  has  ever  been  known  to 


FIG.  403.  —Another  type  of  Small  Carriage  Boiler,  showing  both  tube  plates  inflanged  and 
riveted  to  a  seamless  steel  tube. 


happen  is  that  the  tubes  collapsed  at  the  ends  and  the  boiler 
leaked.  The  water  and  steam  escaping  gradually  reduce  the 
pressure  until  none  is  left — the  result  of  which  is  that  the  tubes 
(a  number  of  them)  are  ruined  and  must  be  replaced." 

On  the  matter  of  metal  and  metal  combinations  suitable  for 
use  in  boilers,  the  following  is  quoted  from  an  excellent  article 
on  the  subject : 


556  SELF-PROPELLED    VEHICLES. 

"The  question  of  the  strength  of  materials  for  boilers  was 
elaborately  tested  some  years  ago  by  the  Franklin  Institute.  It 
was  then  found  that  the  tenacity  of  boiler  plate  increased  with 
the  temperature  up  to  550  deg.  Fahr.,  at  about  which  point  the 
tenacity  began  to  diminish  as  the  temperature  rose.  At  32  deg. 
Fahr.  the  cohesive  force  of  a  square  inch  section  was  56,000  Ibs. ; 
at  570  deg.  it  was  66,500  Ibs. ;  at  720  deg.  it  was  55,000  Ibs. ;  at 
1,050  deg.  32,000  Ibs.;  at  1,240  deg.  22,000,  and  at  1,317  deg. 
9,000  Ibs.  Copper  follows  a  different  law  and  appears  to  be 
diminished  in  strength  for  any  increase  in  temperature.  At 
32  deg.  Fahr.  the  cohesion  of  copper  was  found  to  be  32,800  Ibs. 
per  square  inch  section,  and  exceeds  this  cohesive  force  at  any 
higher  temperature,  the  indications  being  that  the  square  of  the 
diminishing  strength  keeps  pace  with  the  cube  of  the  increased 
temperature.  Strips  of  iron  cut  in  the  direction  of  fiber  were 
found  to  be  6  per  cent,  stronger  than  when  cut  across  the  grain. 
Welding  was  found  to  increase  the  tenacity  of  the  iron,  but  weld- 
ing together  different  kinds  of  iron  was  not  found  to  be  favor- 
able. Overheating  was  found  to  reduce  the  ultimate  strength  of 
plates  from  65,000  to  45,000  Ibs.  per  given  section,  and  riveting 
of  plates  was  found  to  diminish  the  strength  one-third." 

Steam  Feeding  Apparatus.— In  general,  one  of  the  gravest 
difficulties  experienced  in  small  boilers  with  a  large  number  of 
fire  flues  and  consequently  small  clearance,  or  water  space  be- 
tween them,  is  the  danger  of  priming.  This  danger  assumes 
graver  proportions  when  we  consider  the  small  cubic  content  of 
the  cylinders,  which  would  speedily  operate  to  disable  the  engine, 
were  it  not  that  some  means  were  adopted  to  insure  the  delivery 
of  perfectly  dry  steam.  This  end  is  achieved  by  some  boiler-mak- 
ers by  the  use  of  a  baffle  plate,  a  metal  sheet  of  slightly  smaller  di- 
ameter than  the  boiler,  which  is  fixed  above  the  water  level  and 
somewhat  below  the  upper  tube  plate,  so  that  the  small  clearance 
all  around  will  permit  the  steam  to  rise  and  emerge  through  the 
steam  pipe  fixed  in  the  upper  plate,  while  at  the  same  time 
effectually  confining  the  water  circulation  to  the  space  below  it. 
Such  a  device  is  particularly  efficient  when  used  in  connection 
with  a  separator,  or  pipe  of  large  diameter  running  across  the 
diameter  of  fhe  top  plate,  connection  being  made  with  the  steam 
space  at  the  centre  of  the  plate  and,  with  the  feed  pipe  to  the  en- 


SMALL  FLUE  BOILERS.  557 

gine,  by  another  pipe  contained  within  the  separator  and  having 
a  number  of  small  holes  drilled  in  its  length.  In  this  contrivance 
an  extra  precaution  is  found  against  the  escape  of  unvaporized 
water.  Any  form  of  separator  may  be  utilized  for  this  purpose. 
A  device  of  somewhat  similar  description  is  used  in  the  Stanley 
carriage  boilers  as  an  "internal  dry  pipe,"  being  inserted  in  the 
length  of  the  boiler,  closed  at  the  lower  end  and  having  the  en- 
trance very  little  below  the  top  tube  plate.  The  steam  feed  pipe, 
also  closed  up  at  the  bottom  and  having  a  large  number  of  small 
holes  in  its  length,  is  enclosed  within  the  first  pipe  and  emerges 
near  the  top  of  the  shell.  Other  manufacturers  claim  that  the 
end  of  securing  dry  steam  feed  is  insured  by  maintaining  the 
water  level  at  a  point  about  midway  in  the  water  chamber,  thus 
allowing  space  for  extra  expansion,  but  it  is  probable  that  the  ma- 
jority also  employ  either  the  baffle  plate,  the  internal  dry  tube,  or 
some  contrivances  of  their  own  to  add  extra  assurance  of  the  re- 
sult. 


CHAPTER   THIRTY-FIVE. 

OF    WATER-TUBE    BOILERS,     AND    THEIR    USE    IN    STEAM    CARRIAGES. 

Of  Tubular  Boilers  in  General. — The  wide  use  of  tubular 
boilers  in  steam  carriages  and  for  other  purposes  is  explained 
by  the  fact  that  in  its  use  the  problem  of  how  best  to  control 
the  circulation,  to  the  ends  of  quick  steaming  and  higher  dura- 
bility, through  more  uniform  distribution  of  heat,  has  been  best 
solved.  Although  very  many  varieties  of  tubular  boiler  possess 
high  efficiency  as  generators  of  steam,  none  of  them  attain  such 
great  power  for  absorbing  heat  but  what  there  is  still  room  for 
efforts  to  discover  some  means  ofv  neutralizing  waste  in  this 
particular. 

Advantages  of  Controlling  Circulation. — Furthermore,  by 
suitable  arrangements  for  directing  the  rising  and  falling  cur- 
rents, so  that  interference  is  obviated,  another  very  desirable  end 
is  attained — chemical  impurities,  held  in  solution  by  the  water, 
and  precipitated,  so  as  to  form  scale  deposits,  when  it  is  evapo- 
rated, are  prevented  from  locating  and  hardening ;  being  received 
into  mud  drums  suitably  arranged  at  the  lowest  point  of  the 
water  chamber,  where  they  can  be  conveniently  removed.  Ac- 
cording to  statistics  furnished  by  various  authorities  these  scale 
deposits,  consisting  mostly  of  lime  and  other  bnon-conducting 
substances,  interfere  with  the  heat-conducting  properties  of  the 
metal  to  an  enormous  extent:  A  deposit  of  1-16  inch  involving 
a  loss  of  13  per  cent,  of  the  fuel ;  a  deposit  of  l/%  inch,  a  loss  of  25 
per  cent. ;  a  deposit  of  j4  inch,  a  loss  of  38  per  cent. ;  a  deposit  of 
l/2  inch,  a  loss  of  60  per  cent.  The  result  of  allowing  such  in- 
crustations to  increase  will  be  inevitably  that  the  metal  surface 
exposed  to  the  fire  is  burned  out  and  the  boiler  ruined. 

Advantages  of  Water=Tube  Boilers. — With  the  water-tube 
boiler,  on  the  other  hand,  the  fact  that  the  full  force  of  the  steam 
pressure  cannot  bear  on  any  one  extended  surface  involves  that 
in  the  event  of  overheating  or  sinking  of  the  water  level,  only  one 

558 


WATER-TUBE   BOILERS. 


559 


or  two  of  the  tubes  will  burst  with  no  very  serious  consequences. 
Wellington  P.  Kidder,  a  boiler  expert,  enumerates  the  following 
ten  points  of  structural  advantage  in  a  well-made  water-tube 
boiler,  adapted  for  road  wagons  :* 

( i )  The  water  should  not  be  expelled  by  heat  from  the  tubes 
nearest  the  fire  ;  (2)  foaming  and  priming  are  no  more  likely  than 
in  shell  boilers;  (3)  there  need  be  no  joints  near  the  fire;  (4) 
there  may  be  but  few  parts,  easily  and  cheaply  assembled;  (5) 
the  weight  is  about  two-thirds  that  of  a  shell  boiler  of  equal  ca- 


FIG.  404. 


FIG,  405. 


FIGS.  404,  405.— Field  Water-tube  Boiler  and  one  of  the  Field  Tubes,  showing 
inner  tube  and  method  of  controlling  circulation.  A  number  of  such 
tubes  are  hung  over  the  fire-box  of  the  boiler,  as  shown. 

pacity ;  (6)  being  in  sections,  it  may  be  easily  taken  apart  for 
cleaning  or  repairs;  (7)  an  easily  removable  casing  will  deflect 
downward  any  escape  of  steam  or  water,  due  to  breakage  of 
tubes ;  (8)  a  natural  and  rapid  circulation  through  all  tubes  in- 
sured ;  (9)  ample  provision  for  insuring  dry  steam  for  the  cylin- 
ders ;  ( 10)  the  ready  possibility  of  blowing  steam  through  the 
tubes  for  removing  incrustations,  also,  between  them,  for  remov- 
ing soot.  In  a  compliance  with  such  conditions  in  construction 


560  SELF-PROPELLED   VEHICLES. 

he  finds  the  following  eight  points  of  superiority :  ( I )  All  danger 
minimized;  (2)  steam  quickly  generated  ;  (3)  weight  minimized  ; 
(4)  superior  absorption  of  heat  by  inclined  tubes;  (5)  more  heat- 
ing surface  found  on  exterior  of  tubes ;  (6)  less  opportunity  for 
dust  accumulation;  (7)  higher  working  pressure  of  steam  practi- 
cable; (8)  better  elastic  provision  for  expansion.  He  confesses, 
however,  that  most  of  the  really  practical  water-tube  boilers  for 
vehicles  present  some  one  or  all  of  the  following  three  disad- 
vantages: (i)  Too  much  bulk  and  complication;  (2)  liability  to 
foaming  and  priming;  (3)  danger  of  expulsion  of  water  from  the 
tubes  nearest  the  fire  by  overheating.  The  last-named  fault,  if 
not  the  others  also,  is  to  a  large  extent  offset  in  the  De  Dion, 
Weidnecht  and  Clarkson-Capel  water-tube  generators  by  the 
lower  chamber  or  water-jacket;  and  in  the  Lifu  generator  by  the 
trunk  tube  and  water  arch  features.  The  Lifu  generator  is  nearly 
the  most  elaborate  attempt  yet  m?de  to  mechanically  control  the 
water  circulation.  In  the  ideal  water-tube  boiler,  however,  the 
tubes  would  run  across  the  draught  through  a  portion  of  their 
length,  at  least,  thus  making  possible  a  greater  absorption  of  heat, 
through  the  breaking  of  the  air  currents.  This  result  is  im- 
mensely increased  when  the  successive  rows  of  tubes  are  stag- 
gered, so  as  to  still  further  divide  up  the  draught  currents. 

The  Field  Finger=Tube  Boiler. — A  type  of  water-tube  boiler, 
which  has  given  good  service  in  several  steam  carriages,  notably 
•the  Thomson-Ransome  coach,  built  about  1870,  and  the  Velee 
coach,  built  about  1880,  is  of  the  ordinary  fire-engine  upright 
pattern,  with  a  central  smoke  flue  controlled  by  the  form  of 
baffle  damper,  for  regulating  the  heat  currents,  shown  in  the 
accompanying  figure.  Instead  of  five  tubes  or  coils,  it  has  the 
bottom  crown  plate  fitted  with  a  number  of  suspended  "finger 
tubes,"  through  which,  on  account  of  the  peculiar  shape  of  the 
movable  baffle  damper,  the  heated  gases  are  forced  to  circulate. 
Each  of  these  tubes,  which  is  closed  and  rounded  off  at  the  bot- 
tom end,  like  a  chemist's  test  tube,  is  inserted  and  expanded  in 
an  aperture  in  the  crown  sheet.  In  this  inner  open  end,  as  shown, 
is  inserted  a  second  smaller  tube,  which,  in  turn,  depends  from 
a  perforated  globe,  or  a  suitable  collar,  the  three  elements  being 
firmly  attached.  In  the  style  of  Field  tube  shown  in  the  figure, 
the  perforated  globe  carries  a  tapering  ferrule  that  is  driven  into 


WATER-TUBE  BOILERS. 


561 


the  end  of  the  outwardly  hanging  finger  tube,  thus  further  secur- 
ing the  joint. 

The  operation  is  to  be  understood  readily :  The  water  in  the 
lowest  level  of  the  finger  tubes  is  directly  affected  by  the  heat 
of  the  furnace,  and  rises  along  the  sides ;  the  descending  strata, 
working  down  to  take  the  place  left  by  the  rising  mass,  moves 
'through  the  orifice  at  the  top  of  the  globe  and  down  the  central 
tube.  The  circulation  is  thus  perfectly  guided  and,  all  interference 
of  the  rising  and  falling  currents  being  prevented,  the  greatest 
possible  percentage  of  heat  is  utilized.  In  spite  of  the  high  effi- 
ciency of  Field  tube  boilers,  they  have  been  almost  entirely  sup- 
planted in  the  domain  of  motor  vehicles  by  other  types  less  diffi- 
cult to  construct  and  maintain. 


FIG.  406.— The  Geneva  Carriage  Boiler.  This  boiler  consists  of  several  coils 
of  tubing  connected  at  inner  and  outer  extremities  to  headers,  as  shown. 
The  water  and  steam  chamber  above  is  constructed  like  an  ordinary 
flue  boiler. 

The  Geneva  Tubular  Boiler. — Experience,  seems  to  prove 
that  those  manufacturers  who  do  not  use  the  familiar  flue  boiler 
have  some  form  of  multiple  coil  generator,  such  as  are  about  to 
be  described.  Two  of  the  best  designed  among  the  coil  boilers 
are  the  Geneva  and  the  Toledo,  named  respectively  as  the  car- 
riages they  propel.  The  Geneva  boiler  has  the  general  character- 
istics of  water-tube  boilers,  but  has  been  well  described  as  a 
''combination  of  tube  and  flue  boilers."  It  consists  of  six  some- 
what conical  superposed  coils  of  y§  inch  seamless  cold-drawn 


562  SELF-PROPELLED    VEHICLES. 

steel  tubing,  each  17  feet  total  length,  which  are  pinned  and 
brazed  to  a  header,  or  manifold  tube,  both  at  the  centre  of  the 
coils  and  at  the  outside  extremity.  These  two  "headers"  serve 
the  same  ends  as  do  the  head  plates  of  the  generator  just  de- 
scribed ;  being  simply  common  chambers  in  which  the  water  may 
pass  from  one  coil  to  another,  as  impelled  by  the  tendency  of 
circulation.  Thus  the  tendency  within  the  inner  header  is  from 
the  lower  to  the  higher  coils  and  within  the  outer,  the  reverse. 
By  this  means  the  circulation  is  directed  into  its  natural  channels, 
and,  at  the  same  time,  the  water  within  the  coils  is  exposed  to 
the  greatest  possible  area  of  heat.  The  heat  is  also  largely  econo- 
mized, as  in  most  tubular  generators,  by  staggering  the  rows  of 
tubes,  thus  repeatedly  deflecting  and  breaking  up  the  current  of 
burning  gas,  as  it  moves  upward  to  the  vent.  The  water  intake  ij 
at  the  base  of  the  outer  header  tube,  and  the  feed  water,  as  it 
enters,  is  urged  into  the  coils  by  the  pressure  of  the  circulating 
liquid ;  its  temperature  being  immediately  raised  by  contact  with 
the  heated  tubes.  Both  headers  are  secured  by  bolts  to  the  drum 
above  the  tiers  of  coils,  as  shown,  and  open  into  it  by  ports  that 
permit  the  steam  to  be  given  off,  and  any  water  escaping  to  fol- 
low the  general  direction  of  circulation.  This  drum  is,  in  fact, 
a  flue  shell  boiler,  being  pierced  by  16  flues  of  1^4  inch  diameter, 
which  enable  the  super-heating  of  the  steam,  as  the  products  of 
combustion  pass  through  them. 

The  Geneva  boiler  is  8  inches  high,  measured  from  the  base  to 
the  apex  of  the  coned  coils,  and  the  water  chamber  measures  9 
inches  from  the  crown  plate,  giving  a  total  height  of  17  inches. 
It  is  also  17  inches  in  diameter.  The  engine  which  it  supplies  is 
rated  at  6  horse-power,  gross,  which  represents  an  excellent  av- 
erage of  output  for  its  29  1-3  square  feet  of  Heating  surface  being, 
in  fact,  i  horse-power  at  the  boiler  for  each  5  square  feet. 

The  Toledo  Water=Tube  Boiler.— The  Toledo  boiler,  al- 
though differing  considerably  in  some  particulars,  is  constructed 
on  the  same  general  principles  as  the  Geneva.  It  consists  of  an 
annular  water  and  steam  chamber,  formed  by  bolting  together 
two  seamless  steel  shells,  suitably  shaped,  as  shown,  within  which 
eight  slightly  coned  coils  of  ^  inch  steel  tubing  are  attached  at 
top  and  bottom.  The  outer  connection  of  each  of  these  coils  is 
near  the  bottom  of  the  annular  space,  instead  of  in  a  header  of 


WATER-TUBE   BOILERS. 


563 


any  description  and  the  centre  connection  is  near  the  top  of  the 
chamber.  The  attachments  of  all  the  coils,  both  at  the  top  and 
at  the  bottom,  being  on  horizontal  planes,  perfect  circulation  is 
made  possible  from  the  lowest  point  of  heat  contact  upward. 
Because  of  the  excellent  character  of  these  circulation  guides, 
dry  steam  is  fed  to  the  engine,  without  danger  of  priming,  the 
annular  steam  space  serving  as  a  centrifugal  separator.  The 
dimensions  are  19  by  19  inches,  but  il/2  inches  of  asbestos  pack- 
ing gives  a  total  breadth  of  22  inches.  A  heating  surface  of 


FIG.  407.— Sectional  Elevation  of  the  Morgan  Boiler,  formerly  used  on  the 
Toledo  Carriage.  The  disposition  of  the  coils  may  be  understood  from 
these  cuts,  also  the  steam  connections  through  the  superheating  coil. 
The  sectional  view  shows  the  steam  superheating  and  one  of  the  gener- 
ating coils  in  position,  with  connections  indicated  for  other  coils.  As 
shown,  the  steam  enters  a  vertical  tube  somewhat  below  the  top  of  the 
steam  space;  thence  flowing  downward,  through  one  of  the  coils  above 
the  fire  and  out  to  the  engine  through  the  feed  pipe. 

38  square  feet  is  reckoned,  on  which  is  claimed  I  horse-power  for 
every  5  feet,  giving  a  total  of  jl/2  horse-power  at  the  boiler. 

Since  the  two  seamless  shells,  forming  the  annular  water  and 
steam  space,  are  bolted  together — no  rivets  are  used — they  may 
be  readily  taken  apart  for  necessary  repairs  or  cleaning.  The 
coils,  also,  being  connected  to  the  shells  by  joints  of  special  pat- 
tern, may  be  removed  with  ease. 

Heavy  Vehicle  Boilers. — The  achievements  noted  in  the  early 
days  of  the  Nineteenth  Century,  in  producing  generators  capable 


564 


SELF-PROPELLED    VEHICLES. 


of  operating  their  somewhat  unwieldy  coaches,  has  been  more 
than  outdone  in  the  present  day.  Perhaps  among  these  heavy- 
vehicle  generators  none  have  proved  more  efficient  than  the 
Thornycroft,  whose  details  are  shown  in  several  accompanying 
diagrams.  Briefly,  it  consists  of  two  annular  chambers,  one 
above,  one  below,  connected  together  by  168  slightly  inclined 
tubes,  set  four  deep  in  the  tube  plates  and  staggered,  as  shown. 


THE  .IRON  AGE 
FIG.  408.— The  Thornycroft  Steam  Wag-on  Boiler. 

Both  tube  plates  are  steel  pressings,  and  the  upper  and  lower 
chambers  are  built  up  on  them  by  ring-shaped  sections,  suitably 
riveted.  But  the  top  and  bottom  plates  of  the  boiler  are  bolted 
on,  as  shown,  so  as  to  admit  of  their  ready  removal  for  cleaning 
or  repairs.  Fuel,  usually  coke,  is  fed  to  the  fire  through  the 
aperture  in  the  top  of  the  boiler,  and,  since  the  grate  is  situated 


WATER-TUBE   BOILERS.  '  565 

at  a  point  about  the  bottom  of  the  cut,  the  fire  is  confined  below 
the  water  tubes,  touching  no  part  of  the  generator  except  the  in- 
wardly-sloping sides  of  the  lower  drum.  Access  to  the  fire,  for 
the  removal  of  clinkers,  may  be  had  through  the  door  shown  in 
the  lower  drum  at  about  the  level  of  the  grate. 

The  entire  structure  is  sheathed  by  a  suitable  casing,  which 
confines  the  gases  of  combustion,  preventing  their  escape  at  all 
points,  except  the  chimney,  which  is  situated  to  one  side.  Here  a 
forced  draught  is  maintained  by  exhaust  steam,  as  in  a  railroad 
locomotive,  and  the  smoke  and  burned  gases,  having  no  other 
vent,  are  compelled  to  pass  out  through  the  small  spaces  be- 
tween the  slanting  tubes,  thus  giving  off  a  very  large  percentage 
of  their  heat. 

Steam  is  taken,  off  through  the  vent  shown  at  the  left  hand  top 
of  the  upper  chamber,  and  is  fed  to  the  engine  through  a.  steam 
dome.  Later  patterns  of  this  boiler  have  also  a  superheating  coil, 
which  carries  the  steam  from  the  upper  part  of  the  chamber 
to  a  point  directly  over  the  fire,  and  thence  out  through  this 
same  vent.  Water  is  fed  to  this  boiler  by  a  pump  worked  by  a 
worm  gear  on  the  crank  shaft  of  the  engine,  or  by  an  injector, 
when  the  machinery  is  not  in  motion.  Two  safety  velves  are  also 
provided ;  one  blowing  off  into  the  chimney,  the  other,  situated 
at  the  top  of  the  steam  chamber,  into  the  air. 

With  a  generator  of  this  description,  something  over  3  feet  in 
height,  83  square  feet  of  heating  surface  is  obtained  on  about  2.4 
square  feet  of  grate  area.  Its  usual  working  pressure  is  about  175 
pounds  per  square  inch,  with  test  at  350  pounds,  and  sufficient 
steam  is  developed  to  give  20  B.  H.  P.  at  440  revolutions  per 
minute,  which  represents  I  horse-power  at  the  boiler  for  each 
4.15  square  feet  of  heating  surface.  Such  an  average  indicates  a 
highly  efficient  generator. 

The  "Lifu"  Boiler. — One  of  the  most  elaborate  attempts  to 
utilize  the  water  tubes  to  promote  circulation  is  shown  in  the 
"Lifu"  boiler,  which  is  used  on  the  wagons  of  the  Liquid  Fuel 
Engineering  Co.,  of  England — the  name  of  the  boiler  being  de- 
rived from  the  first  syllables  of  the  first  two  words.  Most  of  the 
general  structural  points  may  be  understood  from  the  figure, 
which  shows  three  principal  parts ;  a  circular  trunk  tube  at  the 
base,  from  which  a  large  number  of  curved  tubes  lead  to  the 


566 


SELF-PROPELLED   VEHICLES. 


steam  drum  shown  above.  In  addition  to  these  the  trunk  tube 
is  also  connected  to  the  bottom  of  the  drum  by  a  water  connect- 
ing arch,  both  legs  of  which  are  cast  in  one  piece  with  it  at  oppo- 
site sides.  This  water  arch  makes  the  circulation  complete  along 
natural  lines.  The  water  tubes  are  connected  to  the  trunk  tube 
three  deep  and  staggered.  The  connections  are  made  by  gun 


FIG.  409.— The  "Lifu"  Steam  Boiler,  showing  arrangement  and  inclination 
of  the  tubes.  The  central  steam  drum  terminates  in  two  legs  at  the 
bottom,  which  are  connected  at  either  side  to  the  annular  mud-and-water 
drum  at  the  base,  thus  completing  the  circulation. 

metal  union  nuts,  the  same  kind  of  joints  being  used  in  joining 
to  the  copper  steam  drum.  Each  row  of  tubes,  as  shown,  is 
given  a  spiral  bend  around  nearly  one-third  of  the  circumference 
of  the  drum,  about  nine  inches  from  the  base  and  in  an  opposite 
direction  to  the  next  row,  so  that  complete  water  circulation  is  en- 


WATER-TUBE   BOILERS. 


567 


sured  in  every  direction.  The  whole  structure  is  enveloped  in  an 
iron  sheath  and  packed,  and  heat  is  supplied  by  the  gas  burner 
described  later. 

The  Ofeldt  Tubular  Boiler. — Among  the  interesting  types 
of  tubular  carriage  boilers  may  be  mentioned  the  Ofeldt  gen- 
erator, shown  in  the  accompanying  figures.  As  may  be  seen,  it 
consists  of  an  upright  steam  and  water  drum,  having  a  somewhat 
enlarged  head,  which  serves  as  a  steam  chamber.  Around  this 
upright  drum,  and  connected  to  it  at  top  and  bottom,  are  eighteen 
spirally-twisted  steel  tubes,  which  are  directly  exposed  to  the 


FIG.  410. 


FIG.  411. 


FIG.  410.— Top  View  of  the  Ofeldt  Boiler,  showing  the  feed-water  coil  sur- 
rounding the  generating  coils;  also  attachments  of  generator  coils. 

FIG.  411.— Side  Elevation,  showing  steam  chamber,  generator  coils  and 
burner. 

heat  of  the  burner,  and  control  the  circulation  of  the  water.  The 
construction  of  these  steel  tubes  permits  considerable  expansion 
in  directions  sidewise  of  the  boiler ;  thus  preventing  the  natural 
lengthening  of  the  tubes  under  the  heat  of  the  burner  from  dis- 
turbing the  connections  at  top  and  base.  The  burner  of  this 
boiler  consists  of  a  number  of  tubes,  starting  on  radii  from  a 
central  mixing  drum,  like  the  steam  and  water  drum  already 
described ;  each  one  having  pin-hole  perforations  at  the  top  for 
the  flame  and  being  closed  at  the  end.  The  vaporizing  coil 
passes  over  several  of  the  burner  tubes. 


CHAPTER    THIRTY-SIX. 


FLASH   STEAM    GENERATORS. 

Serpol let's  Flash  Boilers.— The  first  real  impulse  to  the  mod- 
ern steam  carriage  was  the  invention  by  Leon  Serpollet  in  1889 
of  the  famous  "instantaneous  generator,"  known  by  his  name. 
It  consisted  of  a  coil  of  one  and  one-half  inch  lap-welded  steel 
tubing  flattened  until  the  bore  was  of  "almost  capillary  width"- 
this  he  later  increased  to  about  one-eighth  inch — and  this,  sur- 


Fio.  412. 


FIG.  413. 


FlG.  412.  —Earliest  Form  of  the  Serpollet  Flash  Generator  ;  a  coil  of  flattened  steel  tubing. 

FIG.  413.—  Second  Form  of  the  Serpollet  Flash  Generator:  a  series  of  tubes  pressed  as 
shown,  bent  U-shape  and  nested  ;  the  extremities  being  connected  by  joints  and  bent 
unions. 

rounded  by  a  cast-iron  covering  to  protect  the  steel  from  corro- 
sion by  heat,  was  exposed  to  the  fire.  The  result  was  an  ex- 
tremely rapid  generation  of  steam,  the  coil  being  first  heated, 
and  the  water  being  vaporized  almost  as  soon  as  it  was  injected 
into  the  tube.  Later,  he  improved  the  efficiency  of  his  coil  by 
corrugating  its  surface.  With  ?uch  a  generator  of  108  square 
inches  of  heating  surface  more  than  one  boiler  horse  power  could 
be  developed,  the  average  hourly  evaporation  being  forty  pounds 
of  water.  The  usual  working  pressure  was  300  pounds  to  the 

568 


FLASH  STEAM  GENERATORS. 


569 


square  inch,  but  each  tube  could  bear  a  test  of  as  high  as  1,500 
pounds.  One  great  advantage  lay  in  the  fact  that  the  high  ve- 
locity acquired  by  the  steam  and  water  in  the  narrow  tube  served 
to  keep  the  surface  thoroughly  free  from  sediment  and  incrusta- 
tions. For  vehicles  requiring  an  additional  generative  power 
two  such  coils  were  used,  one  above  the  -other,  the  water  being 
injected  into  the  lower  and  the  upper  one  serving  to  superheat 


FIG.  414.— Later  Form  of  the  Serpollet  Flash  Generator,  consisting  of  three  layers  of 
tubing.  The  four  lowest  tiers  shown  form  a  coil  into  which  the  feed  water  is  injected; 
the  second  series  of  six  tiers  are  arranged  "zig-zag,11  like  the  nested  tubes  shown 
in  Fig.  175  ;  the  third,  or  topmost,  series  of  four  tiers  are  also  arranged  "  zig-zag,"  but 
are  flattened  and  then  twisted  as  shown. 

the  steam.  To  stop  the  engine  it  was  necessary  only  to  shut  off 
the  water  feed  pump,  with  the  result  of  stopping  the  generation 
of  steam  at  once. 

In  improved  boilers  of  the  Serpollet  type  a  number  of  straight 
tubes  were  united  by  bent  joints  and  nested,  the  several  layers 
being  connected  in  series.  Moreover,  each  tube  length  was  flat- 


570 


SELF-PROPELLED    VEHICLES. 


tened,  so  as  to  form  a  U-shape,  or  crescent,  in  its  cross-section, 
which  arrangement  greatly  increased  its  evaporating  capacity. 
But  the  most  efficient  form  was  reached  in  the  design  shown  in 
Fig  176,  whidh  shows  three  superposed  sections  of  tubing;  the 
lowest,  four  tiers  of  coil;  the  second,  six  tiers  of  "zig-zag,"  the 


FIG.  415.— Recent  Form  of  the  Serpollet  Flash  Generator.  In  this  type  the  twisted  tubes 
are  placed  at  the  bottom  and  the  "  zig-zag  "  nested  tubes  at  the  top.  The  reason 
for  this  arrangement  is  that  twisting  the  tubes  affords  a  much  larger  heating  sur- 
face ;  hence  these  tubes  are  directly  exposed  to  the  fire. 


successive  tiers  being  staggered,  as  shown ;  the  third,  several 
tiers  of  flattened  tube  twisted  to  angles  of  about  forty-five  de- 
grees. The  water  is  fed  to  the  lowest  section,  which  is  immedi- 
ately exposed  to  the  fire,  being  thence  passed  to  the  second, 
whose  available  heating  surface  is  of  the  greatest  possible  dimen- 
sions, and  finally  delivered,  as  superheated  steam,  from  the  upper- 


FLASH  STEAM  GENERATORS.  571 

most  twisted  coils.  The  several  sections  of  tubing  are  connected 
together  in  series  by  bends  and  unions  outside  the  case,  as  shown, 
and  the  entire  generator  is  enclosed  in  a  double  sheet-iron  casing 
packed  with  asbestos.  By  the  arrangement  of  the  tubing,  as  here 
shown,  the  full  power  of  the  heater,  in  both  draught  and  radi- 
ated heat,  is  utilized,  as  in  the  type  of  boiler  shown  in  Fig.  123, 
but  the  circulation  of  the  water  is  perfectly  under  control  and 
rapid  generation  of  steam  assured.  For  a  six-horse  power  boiler 
of  this  type  the  outside  dimensions,  including  heater  space,  are 
about  2\  x  \\  feet,  the  total  tube  length,  ninety-five  feet,  and  the 
heating  surface,  about  twenty-five  square  feet ;  giving  a  gener- 
ator of  convenient  size  for  a  four-seat  road  carriage. 

Of  Flash  Generators  in  General. — Following  along  the  lines 
of  Serpollet's  famous  "flash"  generator,  with  its  numerous  ad- 
vantages in  point  of  quick  steam,  high  pressure  capacity,  free- 
dom from  scale  deposits,  and  complete  immunity  from  explo- 
sion, several  designers  of  steam  carriages  and  wagons  have  pro- 
duced improved  "boilers"  of  similar  description.  Serpollet's  first 
generator,  as  applied  to  his  light  steam  carriage  of  1889,  was 
merely  a  coil  of  flattened  tubing.  Later  two  such  coils,  con- 
nected in  series,  formed  his  generator,  and  finally  the  compli- 
cated trains  of  coils  and  bent  tubing.  In  the  latest  generators 
described  the  water  is  fed  to  the  lowest  tier  of  tubing,  and  the 
steam  is  taken  off  at  the  top,  as  in  the  several  types  of  coiled 
water-tubed  boilers,  already  described. 

The  contrary  procedure  is  followed  in  most  of  the  really  suc- 
cessful flash  generators  produced  by  other  inventors.  The  Blax- 
ton  generator  feeds  from  the  lowest  water  coil,  but  the  Simpson- 
Bodman,  White,  Automobile  Manufacturing  Co.,  and  others 
feed  from  the  top  and  superheat  the  steam  in  the  lowest  coils. 
This  seems  to  be  the  most  logical  process  for  this  type  of  gen- 
erator, since,  as  the  water  is  explosively  vaporized  by  contact 
with  the  heated  tubes,  it  follows  that  the  progress  should  be 
from  the  lowest  to  the  highest  temperature,  vaporizing  and  super- 
heating the  steam,  rather  than  allowing  it  to  follow  a  course 
from  higher  to  lower  temperature,  with  the  accompanying  con- 
sequence of  loss  of  heat.  By  making  the  tubes  of  sufficient  ca- 
pacity to  vaporize  a  good  quantity  of  water,  surprisingly  high 
temperatures  may  be  obtained  in  a  short  time  and  high  power 


572  SELF-PROPELLED    VEHICLES. 

engines  may  be  driven  with  perfectly  dry  steam.  In  these  par- 
ticulars the  flash  generator  is  superior  to  a  boiler  of  any  type, 
although  it  is  probable  that  its  use  for  light  carriage  purposes 
will  be  very  limited: 

The  White  Flash  "  Boiler."— Among  the  light  steam  car- 
riages equipped  with  flash  generators  may  be  mentioned  those 


FIG.  416.— Diagram  Illustrating  Arrangement  of  the  Vaporizing  Coils  of  the  White  Flash 
Generator,  Elevation.  The  water  is  fed  into  the  centre  of  the  top  coil,  flowing  all 
around  that  coil  and,  in  series,  through  every  other  coil  in  succession.  It  is 
"flashed"  into  steam  somewhere  above  the  lower  coils,  being  taken  off  from  the 
bottom  one.  The  steam  pipe  rises  to  the  top  of  the  generator,  as  shown. 

constructed  by  the  White  Sewing  Machine  Co.,  and  the  Auto- 
mobile Manufacturing  Co.,  the  latter  an  English  concern.  The 
White  generator  consists  of  twelve  superposed  plane  profile  coil?, 
of  quarter-inch  seamless  steel  tubing,  which  are  connected  con- 
tinuously from  top  to  bottom.  The  water,  under  impulse  from  a 


FLASH  STEAM  GENERATORS.          573 

plunger  pump  operated  from  the  crossheacl  of  the  engine,  as  in 
most  steam  carriages,  enters  the  top  coil  at  the  centre  point, 
flowing  thence  around  the  tube  to  the  outer  extremity  of  the 
coil  and  over  again  to  the  centre  of  the  coil  next  below.  The 
same  connection  of  outer  and  centre  extremities  is  maintained 
throughout  the  entire  series  of  coils  until  the  bottom  one  is 
reached.  Here  the  connection  of  the  outer  extremity  is  to  the 
top  of  the  generator  case,  where  is  the  steam  out-take.  This  ar- 
rangement may  be  readily  understood  on  examining  the  diagram. 

The  water,  pumped  into  the  top  coil,  passes  entirely  around, 
and  thence  through  each  coil  continuously,  until  the  bottom  coil 
is  reached.  Somewhere  in  the  downward  travel  it  becomes  va- 
porized, and  by  the  time  it  emerges  from  the  last  coil  it  has  be- 
come superheated  steam.  The  amount  of  water  actually  fed  to 
the  coils  is  determined  by  a  diaphragm  regulator,  which  controls 
a  by-pass  valve,  operating  to  return  any  surplus  feed  to  the  tank. 
The  feed  is  thus  interrupted  when  the  pressure  falls — which  fact 
indicates  the  presence  of  too  much  water  in  the  tubes,  since  the 
amount  of  contained  water  and  the  total  pressure  per  square  inch 
are  in  inverse  proportion.  By  this  means  the  operation  of  the 
generator  may  be  maintained  automatically  at  a  uniform  point ; 
its  output  efficiency  and  the  rapidity  of  steam  generation  being 
dependent  on  the  amount  of  fuel  consumed  by  the  burner,  which 
fact  determines  the  heat  of  the  coils. 

The  pressure  is  indicated  by  an  ordinary  steam  gauge,  which 
shows  a  normal  working  pressure  of  200  pounds  per  square  inch, 
that  being  the  point  at  which  the  tension  of  the  regulator  spring 
is  adjusted.  The  safety  valve,  however,  is  adjusted  to  blow  off  at 
$00  pounds,  a  pressure  which  the  coils  are  said  to  be  able  to  with- 
stand. Under  usual  conditions  of  operation  the  steam  may  be 
superheated  to  about  800  degrees.  As  in  all  flash  generators,  no 
water  is  fed  to  the  coils  when  the  engine  is  not  working,  and  the 
first  essential  act  in  starting  work  is  to  begin  feeding  by  hand, 
vvhich  it  is  necessary  to  do  no  longer  than  to  provide  for  the  gen- 
eration of  steam  for  the  engine.  The  generator  is  of  the  usual 
size  of  light  carriage  boiler,  when  encased  in  its  sheet  iron  and 
asbestos  packing  cover,  and  runs  a  6-horse-power  engine. 

The  automatic  regulator  used  on  the  White  steam  generator  is 
a  true  thermostat  device,  like  that  used  on  the  Blaxton  generator, 
although  regulating  the  fuel  supply  rather  than  the  burner  flame. 


574 


SELF-PROPELLED    VEHICLES. 


Its  position  and  connections  are  shown  on  the  figures  of  the  White 
water  feed  system,  where  it  is  designated  as  Q,  R,  S.  As  shown 
in  an  accompanying  figure,  it  is  constructed  as  follows:  A  tube, 
A,  A,  A,  extends  entirely  through  the  diameter  of  the  generator, 
forming,  in  fact,  the  connection  between  the  two  lowest  coils  of 
the  White  steam  generator,  and  being  connected  at  one  end  on 
the  point,  Q,  and  at  the  other  on  the  sleeve  there  shown.  Within 
this  tube,  A,  is  another  one,  B,  secured,  as  shown,  to  the  head 
piece  at  the  right  hand  end  of  the  tube  in  the  figure.  This  second 
tube  is  preferably  of  copper,  and  around  it,  within  the  tube,  A, 
the  steam  circulates  freely  between  the  two  lowest  coils,  so  long 


FIG.  417.— The  White  Thermostat  Fuel  Feed  Regulator.  A  is  a  tube  extend- 
ing clear  through  the  body  of  the  steam  generator  ana  forming  the 
connections  of  two  of  the  coils,  as  at  Q.  B  is  a  tube  contained  within 
A,  and  around  which  steam  circulates;  C,  a  rod  contained  within  B;  D, 
a  bell  crank  regulating  the  valve,  E,  as  C  lengthens  with  heat;  F,  the 
point  of  the  valve.  R  is  the  valve  chamber,  and  S  the  gasoline  inlet 
chamber  regulated  by  a  needle  valve  on  a  screw-threaded  rod. 

as  the  generator  is  in  operation  ;  thus  determining  its  tempera- 
ture and  consequent  expansion.  Within  this  second  tube,  B, 
again,  is  the  rod,  C,  preferably  of  iron  or  steel,  whose  ratio  of  ex- 
pansion is  smaller  than  that  of  copper  for  all  usual  boiler  tem- 
peratures. This  tube,  C ' ,  bears  upon  the  bell  crank,  D,  normally 
holding  it  in  the  position  shown.  When,  however,  the  tempera- 
ture of  the  steam  or  air  within  the  tube,  A,  has  reached  a  certain 
predetermined  maximum,  the  tube,  B,  of  copper,  expands  accord- 
ingly, lengthening  in  the  direction  of  the  left  of  the  figure,  on 
account  of  being  rigidly  secured  to  the  head  at  the  right.  The 
result  is  that  the  linear  expansion  of  B  and  C  being  unequal,  C 


PLASH   STEAM   GENERATORS. 


is  drawn  away  from  the  bell  crank,  D ,  with  the  result  that  the 
rod,  H,  is  allowed  to  fall  accordingly,  decreasing  or  quite  closing 
the  needle  valve  at  F. 

The  Blaxton  Flash  Generator. — The  Blaxton  generator,  al- 
though differing  in  several  important  particulars,  is  constructed 
on  the  same  general  theory,  consisting  of  a  number  of  super- 


FIG.  418.— Sectional  Elevation  of  the  Blaxton  Flash  Generator. 

posed  plane-profile  coils  of  tubing,  through  which  the  water  is 
passed  in  series,  from  the  lowest  coil  to  the  top,  where  it  is  taken 
off  as  steam.  As  shown  in  the  figure,  the  water  fed  from  the 
pump  passes  direct  to  the  centre  of  the  lowest  coil,  thence  around 
to  the  outer  extremity,  and  to  the  centre  of  the  second  coil.  The 
connections  between  the  coils  of  tubing  are  made  by  nut  joints 
and  unions  outside  the  casing.  The  feed  water  is  pumped  in  by 


376  SELF-PROPELLED   VEHICLES. 

hand  until  sufficient  steam  to  operate  the  engine  is  obtained,  pre- 
cisely as  in  other  flash  generators. 

The  particularly  interesting  feature  of  the  Blaxton  generator 
is  the  device  employed  for  automatically  maintaining  the  con- 
sumption of  fuel  and  of  steam  at  one  ratio.  As  shown  in  the 
diagram,  the  fuel  oil  is  pumped  into  the  short  coil  placed  lowest 
in  the  case,  and,  being  vaporized  by  the  flame,  passes  around  to 
the  burner.  Directly  above,  and  nearly  touching,  the  burner  is  a 
vertical  tube,  closed  at  the  lower  end  and  containing  a  second 
somewhat  shorter  tube. 

The  water,  in  process  of  vaporization,  passes  from  the  outer 
extremity  of  one  of  the  coiled  elements  directly  into  the  inner  of 
these  two  tubes,  the  circulation  being  completed  when  it  passes 
up  between  the  inner  .and  outer  tubes,  through  a  joint,  into  the 
centre  of  the  coil  next  above.  By  this  means  the  temperature, 
and  consequently  the  length,  of  the  outer  tube  is  regulated.  For, 
so  long  as  the  feeding  of  cold  water  continues,  the  water  or  steam, 
passed  through  this  tube,  absorbs  a  large  percentage  of  its  heat, 
thus  preventing  unusual  expansion  lengthwise,  but,  when  the 
supply  is  cut  off,  or  when,  from  any  cause,  the  heat  becomes  too 
great,  the  tube  elongates,  and,  pressing  down  upon  the  gland  of 
the  burner,  closes  the  needle  valve  that  controls  the  fuel  supply. 
By  this  means  the  life  and  usefulness  of  the  generator  is  pro- 
longed, as  much  as  possible,  since  overheating  is  prevented  by 
the  constant  closing  of  the  fuel  feed  valve.  The  Blaxton  gener- 
ator is  thus  rendered  more  highly  efficient  than  most  of  the  aver- 
age "flash  boilers,"  whose  greatest  drawback  is  the  constant 
tendency  to  burn  out,  if  left  long  exposed  to  heat  when  no  water 
is  being  fed  to  the  coils. 

The  generator  herewith  illustrated  measures  5  feet  9  inches  in 
height  and  is  3  feet  square.  It  contains  126  square  feet  of  heat- 
ing surface,  has  a  normal  working  pressure  of  200  pounds  per 
square  inch,  and  can  propel  an  engine  of  25  horse-power.  This 
average  on  heating  surface  is  about  equivalent  to  that  of  a  good 
water-tube  boiler,  although  here  steaming  is  more  rapid. 

The  Simpson  =  Bodman  Flash  Generator. — The  Simpson- 
Bodman  flash  generator  is  probably  the  best  known  after  that  of 
Serpollet,  although  its  use  on  motor  vehicles  is  confined  to  the 
heavy  tractors  and  lorries  built  by  the  firm.  Briefly,  it  consists 


FLASH   STEAM    GENERATORS. 


577 


of  a  number  of  tiers  of  bent  tubing  connected  in  series  with  the 
form  of  connector,  known  as  the  Haythorn  joint,  very  much  after 
the  manner  of  Serpollet's  later  generators.  Unlike  Serpollet's 
tubes,  however,  the  portions  here  exposed  to  heat  are  not  flat- 
tened or  twisted,  but  indented,  as  shown  in  an  accompanying 
figure,  after  the  manner  of  the  Rowe  tube,  so  called  from  the  in- 
ventor of  the  process.  The  tubes  are  also  of  larger  diameter  and 
thicker  walls  than  those  used  by  Serpollet,  and,  according  to  the 


FIG.  419.— Sectional  Elevation  of  one  Form  of  the  Simpson-Bodman  Flash 
Generator  and  Casing1,  showing  the  steam  drum  at  the  right  top  of  the 
casing,  through  which  the  feed  water  is  pumped  to  tne  indented  "Row" 
tubes,  bent  double,  arranged  "zigzag"  and  nested,  like  tne  lubes  of  the 
Serpollet  generator  shown  in  Figs.  175,  176,  177.  The  connections  between 
the  tubes  outside  the  casing  are  by  U-connectors  and  Haythorn  Joints. 

claims  of  the  manufacturers,  can  withstand  a  test  pressure  of  one 
ton  (2,240  pounds)  to  the  square  inch. 

With  a  generator  of  this  description  consisting  of  twelve  two- 
legged  elements,  or  double  tubes,  each  leg  indented  through  a 
length  of  2  feet  6  inches,  3 1/2  -inch  pitch  of  indent — which  gives  a 
total  heating  surface  of  46  square  feet — and  a  grate  area  of  2^4 
square  feet,  an  efficient  temperature  of  400  degrees,  Fahrenheit, 
has  been  obtained  in  25  minutes  from  kindling  the  fire,  and  a 


r.Ts 


SELF-PROPELLED   VEHICLES. 


working  pressure  of  at  least  250  pounds  per  square  inch  in  30 
minutes.  In  fact,  it  is  necessary,  with  this  generator,  to  provide 
against  too  high  a  temperature  of  steam — it  is  not  unusual  under 
running  conditions  that  it  reach  a  temperature  of  1,000  degrees, 
Fahrenheit,  which  would,  of  course,  decompose  the  lubricating 
oil,  if  admitted  to  the  cylinder.  Consequently,  an  essential  fea- 
ture of  construction  is  the  steam  drum,  which  is  an  elongated 
cylinder  containing  one  or  two  U-shaped  tubes.  The  steam  is 
let  into  this  drum,  and  the  feed  water  on  its  way  to  the  top  coil, 
passes  through  the  U-shaped  tubes,  thereby  absorbing  a  goodly 
proportion  of  the  superfluous  heat.  On  leaving  the  drum,  there- 
fore, the  steam  has  reached  a  temperature  sufficiently  low  to  be 
fed  to  the  engine. 

Instead  of  using  any  device  for  regulating  the  heat,  or  open- 
ing the  by-pass  valve,  a  back -pressure  valve  is  fixed  'on  the  feed 


FIG.  420.— Length  of  "Row"  Tube,  such  as  is  used  on  the  Simpson-Bodman 
Generator  for  Producing  an  Enlarged  Heating  Surface.  This  cut  shows 
the  manner  of  making  the  indentations. 

pipe  between  the  by-pass  and  the  generator,  which,  it  is  said,  fur- 
nishes a  much  more  economical  means  of  dealing  with  over-supply 
of  water  than  that  of  returning  it  to  the  tank.  The  steam  is  al- 
lowed to  collect  in  the  drum,  and  superfluous  pressure  is  relieved 
by  an  ordinary  safety  valve  loaded  fairly  high.  This  insures  a 
ready  supply  of  steam  on  hand  to  start  the  engine,  instead  of  re- 
sorting to  the  usual  method  of  pumping  in  water  with  a  hand 
pump. 


CHAPTER   THIRTY-SEVEN. 

THE  TESTING  AND   REGULATING  ATTACHMENTS   OF   STEAM 

BOILERS. 

Boiler  Attachments :  Try-Cocks  and  Water  Glass — In  op- 
erating a  boiler  of  any  design  it  is  essential  both  for  safety  and 
efficiency  that  the  engineer  should  be  kept  constantly  informed 
on  the  level  of  the  water  and  the  pressure  of  the  steam.  For 
this  reason  boilers  are  fitted  with  try-cocks,  water  glass  and 
steam  gauge,  all  of  which  are  depicted  in  accompanying  figures. 
There  are  usually  three  try-cocks,  as  shown,  the  upper  one  in- 
tended for  steam,  the  second  at  the  working  level  of  the  water, 
and  the  third  at  a  fixed  point  above  the  fire  line.  In  conditions 
of  uncertainty  in  the  action  of  the  water  glass  the  engineer  may 
find  out  whether  the  water  level  is  too  low  by  opening  the  lower 
cock,  or  may  find  if  it  is  too  high  by  opening  the  two  upper  ones. 
In  making  test  it  is  necessary  to  leave  the  cock  open  sufficiently 
long  to  discover  whether  all  steam,  all  water,  or  a  mixture  of  both 
is  escaping.  In  large  boilers  it  is  desirable  thus  to  open  the  try- 
cocks  several  times  a  day. 

The  water  glass,  or  water  column,  furnishes  a  ready  means  for 
determining  the  exact  height  of  the  water  in  the  boiler.  It  con- 
sists of  two  cocks  opening  into  collars  arranged  to  be  connected 
by  a  length  of  glass  tubing,  as  shown  in  the  figure.  By  opening 
these  cocks  the  height  of  the  water  may  be  seen  in  the  glass  tube. 
Since  it  is  such  an  important  consideration  in  boiler-  operation 
that  the  water  level  should  be  constantlv  watched,  it  is  necessary 
that  the  water  column  should  be  placed  where  the  engineer  may 
constantly  observe  it.  Thus  it  is  that,  in  steam  carriages  it  is 
disposed  in  the  side  of  the  body  beneath  the  seat,  its  condition 
being  readily  observable  by  the  driver  by  reflection  in  a  small 
mirror  set  to  one  side  of  the  dashboard.  Lamps  are  also  ar- 
ranged behind  it,  so  that  the  level  of  the  water  may  be  observed 
at  night. 

The  water  glass  also  gives  information  on  the  condition  of  the 
water  within  the  boiler,  as  when  oil  or  scum  has  collected  on  the 
surface,  causing  foaming.  Then  the  uneven  fluctuations  in  the 

579 


580 


SELF-PROPELLED    VEHICLES. 


water  level  indicate  the  condition  beyond  doubt.  When  this  con- 
dition is  noted  it  is  time  to  blow  off  the  boiler,  or,  at  least,  to  ob- 
serve carefully  its  operation. 

Troubles  with  the  Water  Glass — Troubles  with  the  water 
glass  that  must  be  constantly  guarded  against  are  stoppage  by 
sediment  and  the  breaking  of  the  glass  tube.  The  former  dim- 


FIG.  421. 


Fio.  422. 


FIG.  421. — Sectional  view  of  a  water  glass,  as  used  on  large  boilers,  showing  water  level 

and  sections  of  stop-cocks,  drain-cock,  tube  packing  and  retaining  nuts. 
FIG.  422. — Section  on  boiler  shell  showing  the  designed  position  of  the  try-cocks:  the  cen- 
ter one  coming  at  about  the  average  water  level. 

culty  may  generally  be  remedied  by  closing  the  lower  cock  and 
allowing  the  steam  from  the  upper  one  to  blow  through  the 
drain  cock  shown  at  the  bottom.  In  case  the  glass  tube  be 
broken  it  is  necessary  only  to  close  both  cocks,  and  insert  a  new 
tube  in  the  collars,  having  first  removed  the  nuts  and  packings  at 
top  and  bottom.  In  order  to  obviate,  as  far  as  possible,  breakage 
of  the  glass  it  is  necessary  to  avoid  too  sudden  changes  of  tern- 


THE  ATTACHMENTS   OF  STEAM  BOILERS.  581 

perature  in  the  column,  when  first  opening  the  cocks,  after  get- 
ting up  steam. 

Most  of  the  water  glasses  used  on  steam  carriage  'boilers  have 
self-closing  valves,  which  operate  to  prevent  the  escape  of  steam 
in  case  the  glass  is  broken.  In  the  use  of  these  valves  particular 
care  is<  needed,  since  they  are  very  liable  to  be  clogged  with  sedi- 
ment or  incrustation,  causing  false  indications  of  the  water  level 
and  enabling  the  boiler  to  be  burned  out  before  the  driver  knows 
that  anything  is  wrong.  Several  carriage  owners,  in  the  writer's 
experience,  have  had  these  valves  removed,  and  contented  them- 
selves with  closing  the  cocks  every  time  the  glass  is  broken.  This 


FIG.  423.  Fio.  424. 

FIG.  423.  -Water  column,  try -cocks  and  water  glass  of  the  "  Locomobile  "  Carriage.  The 
water  column  is  connected  to  the  boiler  at  top  and  bottom,  as  shown.  The  continua- 
tion of  the  lower  pipe  to  the  right  leads  to  the  steam  gauge. 

FIG.  424.— Type  of  check  valve  for  a  water  glass.  As  may  be  seen,  the  cone-shaped  valve 
remains  in  the  position  shown,  so  long  as  the  pressure  is  the  same  at  both  sides. 
When  the  water  glass  is  broken,  the  steam,  coming  through  the  pipe  at  the  left, 
causes  the  valve  to  rise  into  its  seat,  thus  closing  the  opening. 

may  be  a  rather  exceptional  experience,  but  it  is  extremely  de- 
sirable, if  not  imperative,  to 'verify  the  water  glass  reading  by  the 
try-cocks  before  starting  the  carriage. 

The  water  glass  is  an  important  piece  of  mechanism,  and  can- 
not be  too  closely  observed  and  cared  for.  Skilled  engine  drivers 
take  its  record  constantly,  and  so  very  important  is  it  that  no 
error  regarding  the  water  level  should  be  made  that  some  in- 
ventors have  proposed  using  colored  floats  to  attract  the  driver's 


SELF-PROPELLED    VEHICLES. 


eye,  and  enables  readier  reading  of  the  record.  A  supply  of  glass 
tubes  should  always  be  kept  on  hand  in  a  steam  carriage  so  that 
breakage  may  be  immediately  repaired.  Also,  every  possible  pre- 
caution should  be  adopted  to  prevent  the  accumulation  of  sedi- 
ment that  might  obstruct  the  free  passage  of  the  water  into  the 
glass.  It  is  well  to  clear  the  tube  by  flushing  with  steam  at  fre- 
quent periods. 

The  Steam  Gauge. — As  a  means  of  determining  the  power 
output,  a  steam  gauge  is  attached  to  all  well-appointed  boilers. 


FIG.  425.— Interior  View  and  Dial  Face  of  one  Type  of  Steam  Gauge.  The 
steam  is  admitted  through  the  cock  at  the  bottom  of  the  dial  box  into 
a  flattened  and  curved  tube,  which  it  causes  to  straighten  slightly  by  its 
pressure,  thus  operating  the  sector  and  the  hand  on  the  dial  plate. 

This  device  indicates  on  a  -dial  the  degree  of  pressure  generated 
within  the  boiler.  Steam  gauges  are  constructed  with  one  of  the 
two  varieties  of  internal  mechanism.  In  the  first  variety  the  steam 
bears  upon  a  diaphragm,  regulated  to  yield  in  proportion  to  the 
pressure  exerted.  The  second  variety  operates  through  the  ten- 
dency of  a  flattened  and  bent  metal  tube  to  straighten  out  under 
pressure  of  the  steam  or  gas  within  it.  As  shown  in  an  accom- 
panying figure,  a  tube,  flattened  to  an  ellipsoidal  cross  section,  is 
connected  by  one  end  to  a  steam  pipe  leading  direct  from  the 
boiler.  When  the  cock  is  opened,  steam  is  admitted  to  the  tube, 


THE   ATTACHMENTS    OF   STEAM   BOILERS.          583 

its  pressure  tending  to  change  the  flat  section  to  one  more  nearly 
round,  and  in  the  process  causing  the  tube  to  begin  uncoiling  it- 
self in  the  direction  of  a  straight  line  conformation.  Hence  the 
other  end  of  the  tube,  attached,  as  shown,  to  a  link  connected  to 
a  lever  bearing  a  toothed  segment,  tends  to  move,  causing  the 
link  to  move  the  lever.  As  the  lever  is  dragged  by  the  link,  the 
toothed  segment  actuates  a  pinion  carrying  the  hand  of  the  dial 
on  its  spindle,  thus  indicating  on  the  dial  the  pressure  at  work 
in  the  tube. 


FIGS.  426,  427.— Dial  and  Interior  View  of  the  "American"  Duplex  Combined 
Steam  and  Air  Pressure  Gauge  for  Use  on  Steam  Carriages.  The  dial 
has  two  hands;  one  of  them  attached  to  a  sleeve  which  works  over  the 
spindle  carrying  the  other,  in  the  same  manner  as  the  two  hands  of  a 
clock  are  hung.  As  may  be  readily  understood,  the  two  hands  work 
in  opposite  directions,  one  clockwise,  the  other  counter-clockwise,  from 
zero  to  maximum  on  their  respective  scales.  The  sectional  view  shows 
the  mechanism  by  which  this  result  is  accomplished:  two  separate  in- 
lets, for  steam  and  air,  respectively;  two  distinct  flattened  and  curved 
steel  tubes,  each  attached  at  its  end  by  a  link  to  a  lever  and  toothed 
sector  working  on  the  toothed  pinion  concentric  with  the  pivot  of  one  of 
the  hands.  The  two  flattened  tubes,  of  course,  have  different  tensile 
ratios,  causing  them  to  tend  to  straighten  at  different  pressures.  Hence 
the  steam  hand  records  a  maximum  pressure  of  240  pounds,  while  the  air 
hand  records  a  maximum  pressure  of  100  pounds. 

Cause  and  Danger  of  Excessive  Pressures. — Since  every 
boiler  is  calculated  to  supply  steam  to  its  engine  at  a  certain 
maximum  working  pressure — with  light  steam  carriage  boilers 
the  usual  working  pressure  is  between  180  and  200  pounds — 
the  driver  can  readily  find  from  his-  gauge  whether  or  not  full 
power  is  being  generated.  Exceptionally  high  pressures  under 
working  conditions  indicate  a  danger  point,  and  in  small  boilers 
thev  are  verv  often  due  to  a  low  water  lever,  which,  unless  reme- 


584 


SELF-PROPELLED   VEHICLES. 


died,  will  result  in  burning  out.  A  carriage  boiler  holding  a 
proper  supply  of  water  cannot  derive  sufficient  heat  to  generate 
pressures  above  a  certain  fixed  point,  because,  as  will  be  explained 
presently,  the  fire  is  automatically  regulated.  If,  however,  the 
water  has  become  exhausted,  even  though  an  excessive  pressure 
acts  to  shut  off  most  of  the  fuel  supply,  the  metal  of  the  boiler  will 
become  sufficiently  heated  to  collapse  the  tubes.  It  is  the  "dry 
heat"  that  is  most  to  be  feared  in  boilers. 

So  far  as  the  test  resistance  of  small  boilers  is  concerned,  they 
should  be  able  to  endure  pressures  far  beyond  the  ''blow-off 
point"  of  the  safety  valve.  Several  American  carriage  boilers  are 


FIG.  428.  FIG.  429.  FIG.  430. 

FIGS.  428,  429.— Two  Types  of  Low-water  Alarm. 

FIG.  430.— Section  of  a  Type  of  Automobile  Pop-safety  Valve.     A,  the  spring; 
B,  the  valve;  C,  regulating  lever. 

advertised  to  have  been  tested  at  a  "cold  water  pressure"  of  1,000 
pounds  and  over  to  the  square  inch.  This  test  is  made  by  inject- 
ing water  under  such  a  pressure  mechanically  exerted  or  by  fill- 
ing it  from  vertical  tubes  of  considerable  height.  However,  in 
the  absence  of  heat,  this  indicates  only  the  tensile  strength  of  the 
metal.  For  obvious  physical  reasons,  this  is  quite  a  different 
thing  from  the  conditions  brought  about  by  the  action  of  the  heat. 

Safety  Valves;  Construction,  Theory  and  Operation. — The 

design  of  the  argument  up  to  this  point  is  to  satisfy  the  reader 


THE   ATTACHMENTS   OF   STEAM   BOILERS.          535 

that  explosion  in  a  steel-shell,  copper-flued  carriage  boiler  is  very 
nearly  impossible,  and,  further,  that  moderate  care  and  watch- 
fulness can  prevent  the  burning  out  or  collapse  of  the  flues.  The 
unskilled  engine-driver  is  amply  protected,  if  he  only  exercises 
reasonable  prudence  by  the  automatic  burner  regulator,  the  auto- 
matic low  water  alarm,  the  water  glass  and  steam  gauge  in  plain 
sight,  and  lastly  by  a  safety  valve  adjusted  to  blow  off  at  the 
proper  pressure. 

A  safety  valve  is  simply  a  valve  of  ordinary  description,  ar- 
ranged to  close  a  steam  pipe  outlet,  under  pressure  of  a  weight 
or  spring. 

The  safety  valves  used  on  steam  carriages  are  constructed  on 
the  same  general  principles  as  any  of  the  spring  valves  used  on 
locomotives,  or  other  boilers.  They  are  usually  known  as  "pop" 
valves,  from  the  fact  that  the  steam  in  lifting  the  valve  from  its 
seat  usually  makes  a  "pop"  or  sudden  detonation.  As  a  usual 
thing  carriage  valves  are  adjusted  to  a  fixed  pressure,  which  is 
never  disturbed. 

The  Bio  w  =  Off  Cock. — This  is  an  important  attachment  of  all 
boilers,  furnishing  a  ready  means  of  removing  the  water  from  the 
boiler  under  pressure  of  its  own  steam,  which  is  called  "blowing- 
off."  It  is  also  used  in  some  carriages  for  attaching  a  hose  to 
fill  the  boiler  at  starting,  or  for  injecting  water' for  cleaning  the 
interior.  It  is  usually  closed  with  a  box  nut  for  receiving  a 
wrench,  but  sometimes  by  a  cock,  as  in  large  boilers. 


CHAPTER   THIRTY-EIGHT. 

BOILER    FEEDERS    AND    WATER    LEVEL    REGULATORS. 

Of  Boiler  Feeders  in  General.— There  are  two  different  kinds 
of  device  for  feeding  water  to  steam  boilers:  plunger  pumps 
operated  by  the  engine  or  by  a  separate  cylinder;  and  injectors, 
which  raise  and  feed  the  water  by  a  steam  jet  from  the  boiler  it- 
self. Injectors  are  largely  used  for  locomotives,  marine  and  sta- 
tionary boilers,  but  to  the  present  time  almost  not  at  all  in  steam 
road  carriages.  The  principal  reason  for  this  is  that  the  valves 
and  apertures  in  an  injector,  suited  for  a  light  carriage  boiler, 
would  have  to  be  made  so  small  that  they  would  be  constantly 
clogged  with  dirt  and  sediment,  hence  rendering  the  instrument 
inoperative.  Furthermore,  when  in  operation,  an  injector  would 
be  liable  to  fill  the  boiler  too  rapidly,  while  the  pressure  remained 
sufficient  to  raise  the  water,  thus  causing  priming;  and,  if  shut 
off  until  the  water  level  had  fallen  considerably,  would  cause 
damage  to  the  boiler  by  flooding  it,  while  in  an  overheated  con- 
dition. 

Plunger  Pumps  and  By  =  Pass  Valves. — The  plunger  pumps 
used  to  feed  steam  carriage  boilers  are  most  often  operated  from 
the  cross-head  of  the  engine.  Consequently,  so  long  as  the  en- 
gine is  in  motion,  water  is  steadily  pumped  into  the  boiler.  When, 
as  shown  by  the  water-glass,  the  level  is  too  high,  the  by-pass 
valve  may  be  opened,  and  the  water  pumped  from  and  back  again 
to  the  tank.  In  some  carriages  the  by-pass  is  always  operated  by 
hand;  in  others  it  is  also  controlled  by  some  kind  of  automatic 
arrangement.  The  automatic  control  of  the  by-pass  is  extremely 
desirable,  particularly  since  unskilled  engineers  most  often  have 
charge  of  carriages  and  are  exceedingly  liable  to  forget  the  small 
details  of  management.  On  the  other  hand,  many  automatic  de- 
vices get  out  of  order  altogether  too  easily,  and  leave  the  carriage 
driver  to  exercise  his  skill  and  judgment  at  an  unexpected  mo- 
ment. 

586 


BOILER   FEEDERS. 


587 


In  addition  to  the  danger  of  flooding  the  boiler,  the  opposite 
embarrassment  often  occurs — owing  to  some  disarrangement  the 
pump  may  fail  to  feed  enough  water  to  the  boiler,  or  may  not 
operate  at  all.  Then  it  is  necessary  to  use  a  supplementary  feeder, 
generally  a  hand  pump,  or  a  steam  pump  operated  by  a  separate 
cylinder.  Such  supplementary  steam  pumps  and  injectors  are 
commonly  arranged  to  s'tart  automatically,  as  required,  but  may 
also  be  started  by  a  hand-controlled  valve.  Another  advantage 
involved  in  the  use  of  automatically  controlled  steam  pumps  is 
that  water  may  be  fed,  as  required,  to  the  boiler,  after  the  engine 


FIG.  431.— Section  of  a  Type  of  Plunger  Feed  Pump.  As  is  obvious,  the  valve 
opened  by  suction  of  the  up-stroke  is  closed  by  compression  of  the  down- 
stroke,  and  vice  .versa.  This  pump  is  equipped  with  a  double,  or  com- 
pound, valve,  which,  as  may  be  seen,  secures  perfect  balance  in  operation 
with  the  simplest  possible  constructions.  The  stem  of  the  suction  valve 
enters  a  bore  in  the  stem  of  the  outlet  valve.  Referring  to  the  lettered 
parts:  A  is  the  pivoted  lever  working  the  pump  from  the  crosshead  of 
the  engine;  B,  the  fulcrum  point;  C,  the  attachment  or  the  piston  rod, 
D;  E,  the  trunk  plunger;  F,  the  packing  cap;  G,  the  pump  cylinder;  H, 
nut  on  the  valve  chamber  port;  J,  the  valve  chamber;  K,  water  outlet 
valve;  L,  water  inlet  valve. 

has  ceased  motion,  and  it  is  desirable  to  leave  the  carriage  stand- 
ing with  steam  up.  In  this  condition,  however,  a  very  small 
amount  of  water  is  needed,  except  under  unusual  conditions. 

Operating  the  By  =  Pass  Valve. — The  driver  of  a  steam  car- 
riage must  constantly  watch  the  water-glass  in  order  to  inform 
himself  as  to  the  water  level  in  the  boiler.  On  noticing  that  the 
level  is  too  high,  or  is  rising  too  rapidly — the  proper  level  is 
generally  about  two-thirds  up  the  glass — he  opens  the  by-pass 


588  SELF-PROPELLED    VEHICLES. 

valve  by  turning  a  small  wheel  placed  near  the  throttle  lever  be- 
side his  seat.  This  act,  as  already  suggested,  turns  the  water 
forced  by  the  pump  back  again  into  the  feed  tank,  a  three-way 
cock  controlling  its  travel. 

If,  after  the  water  has  been  led  from  the  boiler  for  some  time, 
the  level  begins  to  sink,  it  is  necessary  only  to  close  the  by-pass 
valve,  thus  resuming  the  feed.  If,  from  any  cause,  the  pump 
seems  unable  to  keep  up  the  water  level  in  the  boiler,  and  the 
reading  of  the  water-glass  is  verified  by  the  try-cocks,  thus  show- 
ing that  it  is  working  perfectly  and  is  unclogged  with  sediment, 
a  few  strokes  of  the  auxiliary  hand  pump  will  suffice,  if  no  auto- 
matic steam  pump  be  attached  to  the  carriage. 

Troubles  With  the  Pump. — Since  the  small  water  pumps  at- 
tached to  steam  carriages  are  of  the  simple  plunger  type,  failure 
to  supply  sufficient  water  to  the  boiler  may  generally  be  attributed 
to  loosened  packings  or  to  clogged  check  valves.  The  rapid  sink- 
ing of  the  level  in  the  water-glass  will  indicate  trouble  with  the 
pump,  except  when  ascending  a  high  hill.  In  the  latter  case  the 
fall  of  level  may  reasonably  be  attributed  to  the  unusual  steam 
consumption.  Under  usual  circumstances,  the  trouble  is  due  to 
loosened  packings,  and  this  trouble  may  be  remedied  by  inserting 
new  packings,  although  particular  care  should  be  exercised,  so  as 
not  to  pack  the  plunger  too  tightly  and  cause  breakage.  If  it 
seems  evident  that  the  falling  water  level  is  due  to  clogged  check 
valves — this  is  a  comparatively  rare  occurrence — the  fire  should 
at  once  be  extinguished  and  the  check  valves  opened  and  cleaned. 

Flash  Boiler  Feeders:  The  Serpollet  System. — The  feeding 
apparatus  for  shell  and  water  tube  boilers  is  to  be  adjusted,  either 
automatically  or  by  hand,  solely  with  reference  to  the  mainte- 
nance of  a  proper  water  level.  With  the  feeding  of  flash  gener- 
ators, however,  the  operation  of  automatic  devices  depends  solely 
upon  maintaining  a  certain  predetermined  pressure  and  tempera- 
ture, which  are  properly  in  ratio  to  the  quantity  of  water  being 
vaporized  in  the  tubes,  as  is  not  necessarily  the  case  with  gener- 
ators of  other  types.  It  is  possible,  therefore,  to  maintain  the  feed 
at  the  proper  rate  and  quantity  by  automatic  pressure  regulators, 
such  as  are  used  in  connection  with  steam  carriage  burners,  or  else 
by  some  system  of  uniform  regulation  for  fuel  and  water  pumps. 


BOILER   FEEDERS. 


589 


The  latter  theory  is  adopted  in  the  Gardner-Serpollet  system. 
As  shown  in  the  diagram,  the  fuel  is  fed  to  the  burner,  and  the 
water  to  the  boiler,  through  pumps,  both  of  which  are  operated 
from  the  same  shaft.  The  fuel  pump  is  smaller  than  the  water 
pump  and  its  stroke  is  also  shorter,  as  is  obviously  necessary. 
This  is  accomplished  by  the  use  of  a  stepped  cam,  consisting  of 
a  row  of  eccentric  discs,  of  varying  eccentricity,  which,  placed 
upon  the  rotating  shaft,  may  be  slid  in  either  direction,  thus  vary- 


FIG.  432.— The  Serpollet  Water  and  Fuel  Feed  System.     The  method  of  hang-- 
ing the  stepped  cam  controlling  the  pump  stroke  may  be  here  understood. 

ing  the  lift.  By  shifting  the  cam  inward  toward  the  driving  spur 
the  strokes  of  both  oil  and  water  pumps  may  be  varied  from  zero 
to  maximum  ;  the  cam  surface  being  efficient  in  giving  a  greater 
or  shorter  inward  stroke,  and  in  permitting  an  outward  stroke  of 
equal  length  under  stress  of  the  spiral  spring  attached  below  the 
pump-operating  lever.  These  operations  may  be  readily  under- 
stood by  a  study  of  Fig.  433,  which  is  sketched  from  the  machine 
actually  in  use. 


590 


SELF-PROPELLED    VEHICLES. 


The  liquid  fuel  and  the  water,  being  thus  varied  in  the  amount.; 
given  forth  by  the  pumps,  are  forced,  the  one  into  the  vaporizing 
tube,  passing  over  the  burner,  the  other  into  the  flattened  and 
nested  tubes  of  the  generator.  By  this  means  the  heat  is  increased 
in  ratio  with  the  quantity  of  water  injected,  and  the  working 
pressure  may  be  regulated  to  any  desired  limit.  When,  however, 
the  pressure  has  risen  above  a  certain  fixed  point — it  is  generally 
fixed  at  about  355  pounds  per  square  inch — it  is  able  to  open  the 
spring  safety  valve,  shown  attached  to  the  steam  pipe,  thus  also 
opening  the  by-pass,  so  that  the  water  from  the  feed  pump  is 


FIG.  433.— Serpollet's  Fuel  and  Water  Pumps.  The  water  pump,  a,  and  the 
fuel  pump,  6,  are  operated  from  the  lever  r.  This  is  given  an  up-and- 
down  movement  by  the  link,  d,  whose  stroke  is  varied  by  the  stepped 
cam,  f,  on  which  bears  the  roller,  e,  on  the  rod  pivoted  at  i.  The  rotary 
movement  of  the  cam  shaft,  g,  is  imparted  by  the  spur  wheel,  h. 

thrown  back  into  the  tank.  The  water  from  the  pump  may  be 
forced  through  the  spring  valve,  instead  of  into  the  generator,  by 
the  closing  of  a  check  valve  at  P,  under  steam  pressure.  The 
connections  may  be  readily  understood  from  the  diagram,  which 
also  shows  a  hand-operated  pump  for  making  the  initial  injection 
of  water  into  the  generator  tubes  previous  to  starting  the 
engine. 

The  construction  and  operation  of  the  automatic  by-pass 
regulator,  or  "safety  valve,"  may  be  understood  from  Fig.  434. 
Strictly  speaking,  a  flash  generator  needs  no  safety  valve,  but 


BOILER   FEEDERS. 


591 


its  operation  demands  some,  method  of  preventing  flooding  when 
the  pressure  is  high  enough. 

The  White  Flash  Boiler  Feed  System. — The  water-feed  sys- 
tem of  the  White  steam  carriage  flash  generator  is  based  on  a 
different  theory,  although  the  by-pass  valve  is  controlled  by  a 
spring  and  pressure  device,  as  with  Serpollet.  The  details  of  the 
system  may  be  understood  from  the  accompanying  diagrams, 


FIG.  434.— The  "Safety  Valve,"  or  Automatic  By-Pass  Regulator  of  the  Ser- 
pollet Boiler  Feed  System.  The  steam,  admitted  through  the  tube,  a, 
after  it  has  reached  a  certain  pressure,  opens  the  valve,  6,  compressing 
the  spring,  c.  By  this  action  the  rod,  d,  forces  up  the  valve,  e,  and  the 
spring,  f,  thus  enabling  the  water  from  the  pump  to  pass  from  the  pipe, 
g,  through  the  pipe,  h,  to  the  water  tank. 

which  exhibit  all  the  essential  features.  A  plunger  pump,  A, 
operated  by  a  pivotal  lever  from  the  crosshead  of  the  engine,  B, 
forces  water  from  the  tank,  C,  through  the  pipe,  D,  which,  how- 
ever, divides  into  two  branches  at  the  point,  H,  one  portion  of  the 
water  being  forced  by  the  pump  through  the  pipe,  Ff  to  the  coils 
of  the  generator,  G.  The  pipe,  F,  has  the  air-chamber,  H,  lo- 
cated, as  shown,  between  the  pump  and  the  steam  generator.  An- 


592  SELF-PROPELLED   VEHICLES. 

other  portion  of  the  water  coming  through  the  pipe,  D,  passes 
through  the  pipe,  /,  which  communicates  with  the  lower  chamber 
of  the  pressure  regulator,  K9  to  be  described  later.  Since  the 


FIG.  435.— Diagram  of  the  Fuel  and  Water  Feed  System  of  the  White  Steam 
Carriage.  A  is  the  water  pump  operated  from  the  crosshead  of  the 
engine,  B.  C  is  the  water  tank;  D,  a  pipe  leading  to  the  pump,  and 
branching  off  at  E,  as  shown,  into  J  and  N.  F  is  the  boiler  feed  pipe 
leading  through  the  check  valve,  O,  and  the  air  chamber,  H.  K  is  the 
automatic  by-pass  regulator;  L,  a  pipe  leading  steam  from  the  generator, 
G,  and  allowing  the  water  to  circulate  through  F,  M,  K,  J,  E,  N,  A, 
whenever  steam  pressure  rises  high.  X,  the  pop  valve;  Y,  the  gauge;  Z, 
the  throttle;  T,  the  fuel  tank;  U,  the  fuel  feed  pipe;  Q,  R,  S,  the  fuel 
regulating  and  vaporizing  system  explained  later. 

regulator,  K,  is  operated  only  when  •  the  steam  pressure  has 
reached  a  certain  predetermined  point,  when  the  by-pass  valve  is 
opened,  the  pipes,  F  and  /,  are  not  in  communication  so  long  as 


BOILER  FEEDERS. 


593 


the  pump,  A,  operates  to  feed  water  to  the  coils  of  the  gener- 
ator, G. 

The  regulator,  K,  is  constructed  and  operated  as  shown  in  an 
accompanying  diagram.  It  consists  of  two  chambers,  a  and  b, 
which  are  put  into  communication  on  the  opening  of  the  valve,  cf 
normally  closed  by  the  spiral  spring,  d.  The  rod  carrying  the 
valve,  c,  is  attached  at  its  opposite  end  to  the  head,  e,  which  bears 


FIG.    436.— Section    of   the   Automatic    Boiler    Feed   Regulator   of    the   White 
Steam  Carriage. 

against  the-  metal  diaphragm,  f,  held  between  the  casing  of  a  and 
I  ami  the  cap,  g.  The  operation  is  obvious.  The  port,  /,  shown 
just  above  the  diaphragm,  f,  is  connected  direct  to  the  generator 
by  the  pipe,  L.  When,  therefore,  the  steam  pressure  has  risen 
above  a  certain  predetermined  point,  which  means  that  a  greater 
force  is  exerted  on  the  upper  face  of  the  diaphragm,  /,  than 


594  SELF-PROPELLHD   VEHICLES. 

conies  through  the  head,  e,  from  the  spring,  d,  the  valve,  c,  is 
opened,  making  free  communication  between  the  chambers,  a  and 

b.  Since,  now,  the  ports,  /  and  m,  are  on  the  pipes,  /  and  A/, 
which  are  connected  in  the  system,  as  shown,  the  opening  of  the 
valve  C,  means  that  the  water  circulation  from  the  pump,  A,  is 
through  the  pipes,  /•',  M,  J,  N ;  all  water  being  shut  from  the  coils 
of  the  generator  by  steam  pressure  at  the  check  valve,  0.     So 
soon  soever  as  the  steam  pressure  again  falls  to  normal,  the  valve, 

c,  is  closed  by  the  spring,  d,  and  the  check  valve,  O,  in  F  is  again 
opened,  admitting  water  to  the  coils  of  the  generator  under  pump 
pressure. 

In  connection  with  this  system  of  controlling  the  boiler  feed, 
there  is  a  thermostat  regulator,  shown  at  P  Q,  for  varying  the 
amount  of  gasoline  fuel  fed  to  the  burner,  or  cutting  it  off  en- 
tirely. This,  however,  will  be  explained  in  the  chapter  on  burners 
and  fuel  feed  regulators. 

The  "Victor"  Steam  Air  and  Water  Pumps.— The  auto- 
matic auxiliary  feed  pumps  used  on  the  "Victor"  carriage  and 
shown  in  section  in  the  accompanying  illustration  are  operated 
on  a  principle  which  has  already  been  applied  to  the  steam  air 
pumps  used  in  connection  with  the  Westinghouse  air  brake  on 
many  American  railroad  locomotives.  As  will  be  seen  in  the  il- 
lustration, two  such  automatic  pumps  are  used  on  this  carriage, 
the  one  being  intended  as  an  auxiliary  feed  pump  for  the  boiler, 
to  be  used  in  case  the  regular  feed  pump,  which  is  of  the  double- 
plunger  type,  being  geared  to  and  operated  from  the  rear  axle, 
should  from  any  cause  cease  to  operate.  The  other  pump  is  used 
for  maintaining  the  acquired  air  pressure  in  the  fuel  tank.  The 
steam  is  admitted  through  the  port  marked  "steam  inlet"  in  the 
accompanying  diagram;  this  port  leads  into  an  elongated  cham- 
ber running  the  full  length  of  the  cylinder,  and  of  somewhat 
enlarged  diameter  towards  the  top.  Within  it,  as  may  be  seen 
is  a  vertical  rod,  carrying  a  piston  valve  at  either  extremity.  The 
steam  on  entering,  of  course,  bears  against  these  pristons,  and 
since  the  upper  one  of  the  two  is  of  the  largest  diameter,  it  forces 
it  into  the  position  shown  in  the  cut,  thus  opening  the  port  into 
the  upper  end  of  the  cylinder,  and  forcing  the  piston  downward. 
The  downward  stroke  continues  until  a  shoulder  at  the  lower 
end  of  the  rod,  B,  strikes  the  nut  fixed  above  Gf  opening  the 


BOILER   FEEDERS. 


595 


vaive,  D.  Communication  is  thus  established  between  the  valve 
chest,  in  which  slides  the  double  piston  rod,  A,  and  the  space 
above  the  piston,  C.  Consequently,  steam  is  admitted  above  this 
piston,  which,  being  of  larger  diameter  than  the  piston  below  it, 
forces  it  and  the  valve  rod  downward,  thus  opening  the  steam 
port  into  the  bottom  of  the  cylinder,  and  so  beginning  the  up- 
stroke of  the  piston.  The  up-stroke  continues  until  the  nut  above 
piston,  G,  closes  valve,  D,  thus  cutting  off  steam  from  the  space 


PIG.  437.— Sectional    View    of    the    Valve    Motion    and    Mechanism    of    the 
"Victor"  Auxiliary  Steam  Pumps. 

above  the  piston,  C,  and  again  causing  the  plunger  to  rise.  The 
position  of  the  exhaust  valves  is  such  that  they  are  covered  by 
the  piston  valves  on  rod,  when  these  are  in  position  to  open  the 
inlets,  and  are  opened  again  as  soon  as  the  inlets  are  closed,  thus 
establishing  communication  with  the  exhaust  chamber,  P.  The 
operation  of  the  valves  of  the  pump  is  obvious  and  requires  no 
further  description. 


CHAPTER    THIRTY-NINE. 

LIQUID    FUEL    BURNERS    AND    REGULATORS. 


Of  Liquid  Fuels  in  General. — All  light  steam  carriages,  and 
many  heavier  vehicles  as  well,  use  liquid  fuel,  oil  or  mineral  spirit, 
to  produce  heat  for  their  boilers.  Such  liquid  fuel  is  not  burned 
in  liquid  form,  as  is  oil  in  an  ordinary  lamp,  but  is  vaporized  by 
heat,  the  vapor  or  gas  thus  produced  being  fed  to  the  burner  and 
ignited,  in  the  same  manner  as  ordinary  coal  gas  used  for  light 
or  heat  in  houses.  It  would  be  impracticable  to  carry  gas  in  tanks 
on  steam  carriages,  since  the  difficulty  of  storing  and  replenishing 
the  supply  would  be  greatly  increased.  By  the  use  of  liquid  tuels 
a  vast  saving  is  made  possible,  both  in  space  and  weight,  while 
their  consumption  in  gaseous  form  is  another  element  of  economy. 

Advantages  in  Using  Volatile  Fuels. — A  prominent  English 
authority  on  motor  carriages  gives  the  following  five  considera- 
tions of  advantage  in  the  use  of  liquid  fuels : 

1.  Their  combustion  is  complete,  no  heat  being  lost  in  the  form 
of  smoke  or  soot. 

2.  They  produce  no  ashes  or  clinkers,  which  must  be  periodi- 
cally cleaned  out.    Hence  there  is  no  loss  of  heat  or  drop  in  steam 
pressure,  due  either  to  this  cause  or  to  the  renewal  of  coal. 

3.  The  flues  are  never  incrusted  with  soot,  which  involves  the 
best  conditions  for  use  of  heat. 

4.  The  temperature  of  the  escaping  gases  is  lower  than  with 
a  coal  fire,  since  there  is  no  need  that  the  air  required  for  com- 
bustion should  force  its  way  through  a  thick  layer  of  burning 
fuel.     Whence  the  uptake  temperature  is  generally  about  400°, 
Fahrenheit,  instead  of  between  600°  and  700°,  as  with  the  use  of 
coal  fire. 

5.  Since  the  fuel  is  burned  in  fine  particles,  in  close  contact 
with  the  oxygen  of  the  air,  only  a  small  excess  of  air  over  that 
actually  required  for  combustion  is  admitted  to  the  burner.    The 
opposite  is  the  case  with  coal. 


BURNERS   AND    REGULATORS.  597 

As  may  be  readily  surmised,  the  calorific  value  of  liquid  fuels 
is  far  greater  than  that  of  coal.  It  has  been  estimated  that,  taking 
the  two  weight  for  weight,  petroleum  oil  has  about  twice  the 
heat  efficiency  of  coal.  Since,  therefore,  equal  weights  of  both  vari- 
eties of  fuel  occupy  about  equal  spaces,  it  follows  naturally  that 
petroleum  products  are  far  more  economical  and  serviceable  for 
use  in  vehicles  of  any  description,  or  in  boats  and  ships,  where 
the  considerations  of  weight  and  space  occupied,  in  ratio  to  the 
power,  are  all-important. 

The  liquid  fuels  most  commonly  used,  are  kerosene  and  gaso- 
line, both  being  vaporized  by  the  heat  of  the  burner;  a  kindling 
flame  from  liquid  gasoline  or  alcohol  vapor,  or  a  specially  ar- 
ranged detachable  auxiliary  vaporizer,  or  "torch,"  being  used  at 
the  start,  and  until  the  vaporizing  tubes  are  thoroughly  heated. 
Kerosene  is  less  suitable  for  steam  carriage  burners  than  is  gaso- 
line. A  far  higher  temperature  is  required  to  vaporize  it,  and  a 
larger  evaporating  surface.  Furthermore,  it  requires  large,  bulky 
and  complicated  burners  to  consume  its  vapor,  and  very  frequent- 
ly produces  an  excessive  amount  of  carbonaceous  residuum,  which 
necessitates  periodical  cleaning  and  considerable  trouble  in  gener- 
ating heat.  Gasoline,  on  the  other  hand,  being  a  highly  distilled 
product  of  petroleum,  is  more  readily  vaporized  than  kerosene,  re- 
quiring generally  no  greater  temperature  than  may  be  obtained  by 
passing  the  supply  pipe  up  through  one  flue  of  the  boiler  and  down 
through  another.  Such  heating  as  this  would  have  very  small 
effect  on  kerosene.  The  burners  used  for  gasoline  are  simpler 
and  more  readily  regulated  than  those  used  for  kerosene.  They 
may  also  be  made  much  lighter  in  comparison  to  their  heating 
power  and  are  less  difficult  to  fire  up  at  the  start.  All  these  points 
are  distinctly  advantageous,  if  not  imperative,  on  a  light  steam 
carriage,  intended  for  amateur  engine  drivers.  On  a  heavy 
wagon,  intended  to  be  managed  by  skilled  engineers,  they  are  of 
less  importance,  and  may  be  readily  superseded  by  the  more  com- 
plicated devices  for  using  the  cheaper  fuel. 

The  Gasoline  Burner. — Very  nearly  the  typical  gasoline  burner 
for  steam  carriages  is  shown  in  an  accompanying  figure.  It  con- 
sists of  a  flattened  cylindrical  chamber,  pierced  from  head  to  head 
by  a  number  of  short  tubes,  each  of  which  is  expanded  into  the 
holes  prepared  for  it  and  flanged  over  to  make  a  secure  joint, 


598 


SELF-PROPELLED    VEHICLES. 


somewhat  after  the  manner  of  a  well-made  boiler  flue  attachment. 
These  air  tubes,  as  they  are  called,  are  open  to  the  air  at  top  and 
bottom,  having  no  communication  with  the  interior  of  the  cylin- 
drical chamber  above  referred  to.  The  gasoline  enters  the  cham- 
ber, from  a  nozzle  at  the  end  of  the  feed  pipe  and  through  a  tube 
entering  at  one  side  of  the  cylinder  and  extending  inward  about 
two-thirds  of  the  diameter.  This  tube  is  called  the  "mixing  tube," 
and  its  function  is  to  make  a  mixture  of  air  and  gasoline  vapor 


FIG.   438.— Plan   and  Part   Section   of  a  Typical   Gasoline   Burner   for   Steam 
Carriage  Use. 


that  will  burn  readily  in  the  atmosphere.  Having  entered  the 
cylindrical  chamber,  there  is  no  avenue  of  escape  for  the  in- 
flammable gas  except  through  the  circular  series  of  pin-holes, 
which  surround  each  one  of  the  air  tubes,  as  may  be  seen  on  the 
cut  of  the  top  of  this  burner.  It  is  at  these  minute  perforations 
that  the  gasoline  gas  is  ignited,  the  combustion  being  rendered 
perfect  by  the  air  admitted  through  the  air  holes  previously  men- 
tioned. 


BURNERS  AND  REGULATORS.          599 

The  Storing  and  Feeding  of  Gasoline. — The  liquid  gasoline 
for  supplying  gas  to  the  burner  of  a  steam  carriage  is  carried 
in  a  tank,  disposed  generally  to  the  front  of  the  body,  and  suffi- 
ciently separated  from  the  burner  to  avoid  all  dangers  that  might 
arise  from  leaks  or  overheating.  Within  this  storage  tank  a  good 
pressure  of  air  is  maintained — generally  between  45  and  50 
pounds  to  the  square  inch — from  a  separate  air  tank,  supplied  by 
a  pump.  This  pressure  is  sufficient  to  force  the  liquid  gasoline 
into  the  vaporizing  tubes,  when  the  supply  cock  is  opened.  After 
it  has  been  vaporized  the  circulation  continues,  as  controlled  by 
the  steam  pressure  diaphragm  regulator,  which  operates  a  needle 
valve  on  the  tube  supplying  the  burner,  the  amount  of  gas  and 
liquid  gasoline  moving  between  the  supply  tank  and  the  burner 
being  thus  determined.  If  the  fire  is  blown  out  in  the  draughts 
created  by  travel,  the  difficulty  may  be  generally  remedied  by  using 
higher  air  pressures  in  the  tank.  Some  drivers  have  used  as  high 
as  100  pounds  and  over. 

The  pressure  in  the  air  tank  is  produced  and  maintained,  either 
by  a  small  hand  pump,  such  as  is  used  to  inflate  pneumatic  tires 
— this  method  is  used  on  several  well-known  American  steam 
carriages — or  else  by  some  such  specially  designed  pump,  as  is 
used  on  the  Victor  carriage,  or  some  others  described. 

The  Automatic  Fuel -Feed  Regulator. — The  fuel-feed  regu- 
lator, of  which  there  are  several  serviceable  forms,  is  one  of  the 
most  necessary  attachments  of  a  steam  carriage.  Generally,  it 
consists  of  a  diaphragm,  which,  actuated  by  steam  pressure  from 
the  boiler,  automatically  closes,  or  partly  closes,  a  needle  valve, 
thus  regulating  the  amount  of  fuel  fed  to  the  burner.  Several  such 
apparatus  are  shown  in  section  in  accompany  cuts.  There,  as 
may  be  seen,  the  diaphragm  is  fixed  across  the  tube  leading  from 
the  steam  space  of  the  boiler.  Against  its  inner  side  bears  'a  solid 
head,  or  pressure  cap,  carrying  a  rod,  at  the  farther  end  of  which 
is  a  needle  valve.  The  pressure  cap  is  normally  held  against  the 
diaphragm  by  a  strong  spring.  When  sufficient  steam  pressure 
bears  upon  the  diaphragm,  the  spring  is  compressed,  allowing 
the  rod  attached  to  the  head  to  be  pushed  inward,  thus  regulating 
the  needle  valve,  according  to  requirement.  The  instrument,  thus 
formed,  consists  of  two  parts.  The  one  is  the  pressure  cham- 
ber containing  the  spring,  whose  pressure  on  the  head  is  regu- 


600 


SELF-PROPELLED    VEHICLES. 


lated  by  an  adjusting  screw,  through  the  shaft  of  which  passes 
the  valve  rod.  The  other  is  the  gasoline  chamber,  into  which 
the  fuel  for  the  burner  is  admitted  to  the  left  of  the  point  of  the 
needle  valve ;  its  outlet  being  controlled,  as  shown,  by  two  hand- 
wheel  valves — one  leading  to  the  main  burner  through  the  mix- 
ing tube,  the  other  being  intended  to  let  out  a  sufficient  supply 
of  gasoline  to  the  starting  device,  which  may  be  a  detachable 
"torch,"  or  auxiliary  vaporizer,  or  some  arrangement  of  drip  cup 
and  preliminary  generating  coil.  This  arrangement  of  the  valves 
is  shown  in  different  cuts  of  burners  and  automatic  regulators, 
being  there  sufficiently  designated,  Thus,  as  shown  in  the  figures, 


FIG.  439.— Fuel  Feed  Regulator  of  a  Steam  Carriage  Burner,  intended  for 
Use  with  "Torch"  Burner  Kindler  or  Auxiliary  Vaporizer.  A  is  the  hand 
wheel  and  needle  valve  regulating  the  feed  to  the  main  burner;  B,  the 
hand  wheel  and  valve  for  operating  the  torch;  C,  the  spring  and  header 
attached  to  the  main  valve  rod;  D,  the  diaphragm  against  which  steam 
bears,  regulating  the  main  valve  according  to  pressure.  The  liquid 
gasoline  is  admitted  at  a  port  on  the  left-hand  extremity  of  the  regu- 
lator tube,  near  the  end  of  the  needle  valve  on  the  main  rod. 

the  valve  rod,  in  entering  the  gasoline  end  of  the  regulator,  passes 
through  a  stuffing  box,  so  as  to  prevent  all  leakage  at  that  end. 

Of  course,  until  there  is  sufficient  heat  generated  to  vaporize 
gasoline  for  the  regular  burner  and  generate  steam  pressure  in 
the  boiler,  the  automatic  regulator  cannot  operate,  as  described, 
and  the  flow  of  gasoline  to  the  starting  burner  or  vaporizer  is 
regulated  solely  by  the  hand  valves. 

Another  form  of  regulator,  shown  in  an  accompanying  cut, 
used  on  steam  wagons,  has  the  advantage  of  simplicity  in  this 
particular,  doing  away  with  both  spring  and  stuffing  box.  The 


BURNERS  AND  REGULATORS.          601 

diaphragm  has  concentric  corrugations,  and  to  its  centre  is  at- 
tached a  valve  rod  having  longitudinal  groovings  to  permit  the 
fuel  to  enter  the  feed  tube  in  such  quantities  as  the  pressure  on 
the  other  face  of  the  diaphragm  will  permit.  Steam  pressure, 
being  thus  brought  to  bear,  tends  to  deform  the  diaphragm ;  hence 
compressing  the  valve  rod  and  decreasing  the  rate  and  quantity  of 
fuel  feed.  The  fuel  is  supplied  from  the  storage  tank  through  the 
port  into  the  lower  chamber  of  the  two  formed  by  the  diaphragm, 
as  may  be  readily  understood. 


FIG.  440.— Gasoline  Burner  Regulator,  operating  with  a  corrugated  dia- 
phragm, like  a  steam  gauge.  A  is  the  inlet  for  steam;  B,  the  inlet  for 
liquid  gasoline;  C,  the  port  leading  to  the  burner;  D,  the  diaphragm;  E, 
the  head  on  the  grooved  rod  of  the  valve;  F,  the  steam  chamber;  G,  the 
gasoline  chamber. 

Constructional  Points  on  Gasoline  Burners. — Several  steam 
carriage  burners  are  formed  by  riveting  together  a  steel  flattened 
cylindrical  pressing  and  a  plane  disc,  as  shown  in  a  former  figure, 
inserting  and  expanding  the  draught  tubes  into  suitably  arranged 
perforations,  as  is  done  with  the  flues  of  boilers.  Such  a  con- 
struction is  apt  to  be  faulty,  however,  owing  to  the  fact  that  the 
steel  plates  tend  to  warp  under  the  influence  of  heat,  causing  the 
draught  tubes  to  leak,  and  the  attachments  to  wear.  The  danger 
of  these  accidents  has  moved  several  inventors  and  manufacturers 
to  design  and  produce  burners  formed  with  a  cast  top  and  steel 
plate  base,  or  to  cast  both  elements.  By  the  use  of  castings  warp- 
ing is  positively  prevented,  and  leaking  at  the  joints  of  the  draught 
tubes  is  obviated. 

One  of  the  best-known  burners  of  this  construction  is  that 
widely  known  as  the  "Dayton,"  which  possesses  the  additional 
feature  of  supplying  gas  for  the  burner  flame  through  annular 
openings  around  each  of  the  draught  tubes,  instead  of  using  the 


602  SELF-PROPELLED   VEHICLES. 

"pin-hole"  design,  already  described.  It  is  possible  to  construct 
with  this  feature,  since  the  air  tubes  are  cast  in  one  piece  with 
the  head  and  base  plates,  being  afterward  reamed  out,  so  as  to 
make  them  uniform  in  size.  In  addition  to  this  air  opening,  a 
counter-bore  is  sunk  in  the  top  plate  of  the  burner,  and  a  steel 
washer  is  fitted  into  it,  leaving  an  annular  opening  for  the  passage 
of  gas  in  the  inside  of  the  washer.  The  outside  of  the  washer 
has  a  number  of  small  openings  in  it,  so  that  each  air  tube  is  sur- 
rounded by  two  concentric  circles  of  flame.  This  construction 
affords  a  very  large  heating  capacity,  and  also,  as  is  claimed, 
prevents  the  top  of  the  burner  from  cracking,  also  less  liability 


FIG.   441.— The  Dayton   Burner,   showing  the   Starter  Box  and  Regulator  in 
Position. 

of  chocking  with  rust,  dust  or  carbonized  particles,  which  is  a 
frequent  source  of  annoyance  with  "pin-hole"  burners. 

An  interesting  variation  on  the  common  type  of  steam  carriage 
burner  is  presented  in  the  device  used  on  the  Whitney  carriage. 
This  burner  is  made  with  the  usual  top  and  base  plates,  the  air 
tubes  being  inserted  and  flanged  over,  as  already  described.  In- 
stead of  the  usual  slits  or  punctures  for  the  gas  to  pass  through, 
each  tube  is  perforated  on  each  90°  of  its  circumference ;  thus 
making  communication  to  the  interior  of  the  gas  chamber  within 
the  flattened  cylinder.  A  second  tube  is  then  inserted  within  the 
first,  fitting  closely,  except  for  a  slightly  diminished  circumfer- 
ence at  about  the  level  of  the  perforations  just  mentioned.  The 


BURNERS   AND   REGULATORS. 


603 


gas  from  the  mixing  chamber,  entering  these  perforations,  passes 
between  the  two  tubes,  and,  mixing  at  the  top  of  the  tube  with 
the  air  drawn  through  the  draught  tube,  produces  a  very  hot 
flame,  as  in  the  ordinary  type  of  Bunsen  gas  burner.  A  similar 
effect  is  gained  with  several  types  of  burner  using  a  number  of 
straight  perforated  tubes  with  air  spaces  between,  thus  ensuring 
plenty  of  air  for  combustion  from  both  sides  of  the  flame. 


FIG.  442.— Plan  and  Sectional  Elevation  of  the  White  Burner. 

The  White  Gasoline  Burner. — The  burner  used  on  the  White 
carriage  is  also  an  interesting  departure  from  the  common  types. 
As  shown  in  the  plan  and  sectional  sketches,  it  consists  of  an 
upper,  or  face,  plate  of  cast  iron,  having  concentric  corrugations, 
between  which  are  the  draught  tubes,  connecting  the  top  and 
base  plates,  as  in  other  burners.  Instead,  however,  of  the  usual 
pin-holes  or  slits  around  the  openings  of  the  draught  tubes,  there 
are  concentric  rows  of  radially  disposed  slits  across  the  raised 
corrugations  on  the  face  of  the  upper  plate.  The  sketch  shows 


604 


SELF-PROPELLED    VEHICLES. 


FIG.  4.43.  — Usual  pattern  of  "  torch"  head  and  starting  "  torch,''  used  on  several  American 
steam  carriages.  The  head  parts  are  lettered  as  follows:  A,  body  of  head;  B,  threaded 
cap;  C  and  D,  nuts  working  on  screws,  F  and  G,  on  rod,  E.  Screw,  G,  gives  attach- 
ment to  the  collar  on  the  valve  stem,  as  shown  at  B,  in  the  succeeding  figure. 


FIG.  444.— Showing  the  torch  in  position.  By  reference  to  Fig.  217,  it  may  be  readily  un- 
derstood that  the  head  of  the  torch,  C,  is  attached  to  a  nipple  on  B  by  screw,  G;  the 
bent  tube  being  thrust  through  a  port  in  the  burner  casing  so  as  to  come  directly  over 
the  flre;  the  nozzle  entering  the  mixing  tube  by  the  side  of  the  nozzje  on  the  main 


BURNERS   AND   REGULATORS.  605 

these  in  larger  number  than  on  the  burner  in  actual  use,  which, 
being  about  14  inches  in  diameter,  has  the  slits  arranged  at  inter- 
vals of  about  y2  inch. 

Obvious  constructional  and  practical  advantages  inhere  in  this 
design,  since:  (a)  The  draught  tubes,  being  separated  from  the 
flame,  cannot  be  loosened  by  the  heat,  (b)  Being  arranged  to 
either  side  of  each,  circle  of  flame,  sufficient  oxygen  is  supplied  to 
produce  perfect  combustion,  (c)  The  construction  is  such  that 
there  is  no  danger  of  warping  or  deformation  under  heat. 

The  automatic  thermostatic  regulator,  described  above,  is  used 
with  this  burner.  The  incoming  gasoline  supply  goes  to  the  pre- 
liminary vaporizer,  C,  over  the  pilot  burner,  G,  thence  through 
the  vaporizing  tubes,  and  through  the  regulator,  and  into  the 
mixing  chamber,  whence  it  emerges  through  the  fire  slits,  D,  D. 

Methods  of  Starting  the  Fire:  The  "Torch."— There  are 
several  methods  of  starting  the  fire  in  gasoline  carriage  burners, 
each  having  been  devised  as  an  improvement  in  way  of  simplicity 
and  ease  of  operation. 

The  most  familiar  method  of  starting  the  fire  is  by  the  use  of  a 
removable  auxiliary  vaporizer,  or  "torch,"  such  as  is  used  on  the 
"Mobile,"  and  several  other  well-known  steam  carriages.  It  con- 
sists, briefly,  of  a  continuous  iron  tube  bent  double  at  the  centre, 
as  shown,  and  having  a  cock  and  screw  head  at  one  extreme  and 
a  tapering  nozzle  at  the  other.  This  instrument  is  held  in  the 
fire  of  an  ordinary  stove,  or  .over  a 'fire  kindled  with  cotton  waste 
saturated  with  gasoline,  until  it  reaches  a  temperature  usually 
described  as  a  "sizzling  heat,"  which  is  to  say  the  point  at  which 
any  moisture  applied  to  its  surface  will  occasion  the  familiar 
"sizzle,"  noted  when  water  is  dropped  on  a  stove  lid.  It  is  a  heat 
just  below  the  point  where  iron  begins  to  redden.  Some  author- 
ities advise  that  the  "torch"  be  heated  to  a  "dull  red,"  as  that  will 
give  a  better  temperature,  when  it  is  inserted  in  the  burner. 

The  "torch,"  having  been  heated,  its  double  bent  tube  is  in- 
serted in  an  aperture  in  the  burner  casing,  designed  to  receive  it, 
the  screw  and  valve  end  being  attached  at  an  aperture  controlled 
by  the  pin  valve  and  hand-wheel,  B,  in  the  sectional  cut  of  the 
automatic  regulator,  and  its  nozzle  being  inserted  in  the  same 
aperture  as  is  penetrated  by  the  nozzle  controlled  by  the  pin  valve 
and  hand-wheel,  A,  in  the  same  figure.  This  done,  the  hand- 


606 


SELF-PROPELLED    VEHICLES. 


wheel,  B,  is  turned,  so  as  to  open  the  needle  valve  at  the  end  of 
its  stem,  as  far  as  is  required ;  thus  admitting  liquid  gasoline  into 
the  double  bent  tube  of  the  torch  through  the  screw  and  valve 
attachment.  The  result  is  that,  passing  through  the  heated  tube, 
it  is  vaporized,  and  the  burner  is  ignited  by  a  match  or  paper  lamp- 
lighter thrust  through  an  aperture  prepared  for  that  purpose. 

An  Auxiliary  Coil  Starting  Device. — The  starter  used  with 
the  "Dayton"  burner,  already  described,  is  shown  in  an  accom- 
panying cut.  There,  as  may  be  seen,  a  small  box,  called  a  "starter 
box,"  is  attached  at  one  side  of  the  burner  It  contains  a  short 


FIG.  445.— Starter  Box  and  Diaphragm  Regulator  of  the  "Dayton"  Burner. 
The  parts  are:  A,  segmental  plate  and  collar  at  opening  of  the  mixing 
tube;  B,  thimble  on  starter  box  containing  supply  pipe  to  tne  mixing 
tube  and  burner;  C,  starting  valve;  D,  knuckle  joint  for  connecting  con- 
trol valve  to  driver's  seat;  E,  head-piece  of  the  diaphragm  regulator. 

coil  of  tubing,  into  which  liquid  gasoline  may  be  admitted  by 
opening  the  valve  marked  "starting  valve."  A  few  drops  of 
liquid  gasoline  are  then  allowed  to  drip  into  the  "starting  cup," 
beneath  the  coil,  and  this,  set  on  fire,  will  speedily  generate  suffi- 
cient gas  to  light  the  pilot  burner,  from  which,  in  turn,  the  main 
burner  may  be  kindled  as  soon  as  the  vaporizing  tubes  are  suffi- 
ciently heated.  As  soon  as  this  point  is  reached  the  needle  valve 
to  the  main  burner,  shown  at  the  right  hand  of  the  starter  box, 
is  opened,  admitting  gas  through  the  nozzle  into  the  mixing  tube. 
By  closing  this  valve,  the  main  fire  may  be  shut  off,  as  desired, 


BURNERS  AND   REGULATORS. 


607 


although  the  pilot  light  continues  burning,  until  extinguished  by 
shutting  off  its  supply  of  gas,  which  is  never  modified  in  any  way, 
being  out  of  reach  of  the  automatic  regulator  controlling  the  .fuel 
feed  to  the  main  burner. 


The  Kelly  Vaporizer  and  Burner. — The  preliminary  vaporiz- 
ing device  used  on  the  Kelly  burner  is  equally  interesting  in 
operation.  A  "generator"  box,  attached  to  the  outside  of  the 


FIG.  446.— The  Starter  Box  and  Control  Valve  of  the  Kelly  Burner.  A,  union 
joint  to  supply  pipe;  B,  gas  orifice  leading-  direct  to  the  main  burner; 
C,  drop  drip  cup  and  bottom  of  case;  D,  sub-flame  valve;  E,  check  on 
valve  to  prevent  turning  by  vibrations  of  travel;  F,  packing  nut  on  the 
main  fire  valve;  G,  knuckle  joint  to  carry  rod  to  seat;  H,  opening  to 
screw  on  the  diaphragm  regulator;  K,  the  alcohol  lamp  hung  in  position 
to  start  vaporizing  and  fire  the  burner. 

burner  casing,  encloses  a  portion  of  the  tubing  leading  from  the 
supply  pipe  and  gasoline  tank,  and  also  attachments  for  the  vari- 
ous valves.  The  bottom  of  this  box  contains  a  drip  cup,  and  is 
arranged  to  open  on  a  hinge,  so  as  to  allow  of  attaching  an  ad- 
justable alcohol  lamp,  as  shown  in  the  accompanying  cut.  In 
order  to  begin  the  process  of  vaporizing  the  fuel  previous  to  light- 
ing the  burner,  the  movable  drip  cup  and  bottom  of  case  is  opened 
out,  as  shown  at  C  in  the  cut,  and  the  alcohol  lamp,  K,  is  hung 


608  SELF-PROPELLED   VEHICLES. 

beneath  the  opening.  A  flame  is  kindled  in  this  lamp,  and,  after 
it  has  burned  several  minutes,  the  "sub-flame  valve,"  D,  is  opened, 
and  the  lamp  removed.  At  this  point  it  is  possible  to  ignite  the 
vaporized  gasoline  at  the  opening  of  the  "sub-flame  valve,"  by. 
applying  a  match  through  the  small  drop  door  shown  near  the 
top  of  the  generator  box.  After  the  flame  has  burned  about  a 
minute  more,  the  main  fire  valve  may  be  opened,  slowly  at  first, 
in  order  that  the  burner  and  supply  pipes  may  be  thoroughly 
heated.  As  soon  as  the  burner  is  thoroughly  started  the  small 
door  at  the  base  of  the  generator  is  closed.  In  case  the  alcohol 
lamp  has  been  lost,  the  drip  cup  formed  on  the  inner  face  of  this 
door  may  be  used  for  the  preliminary  vaporizing  flame  by  par- 
tially opening  it  and  igniting  the  contained  gasoline  with  a  match. 
Gasoline  may  also  be  burned  in  the  lamp  in  case  no  alcohol  can  be 
obtained. 


CHAPTER   FORTY. 

SIMPLE   STEAM   CARRIAGE   ENGINES. 

American  Steam  Carriage  Engines. — In  the  particular  con- 
struction of  steam  engines  for  use  on  motor  road  carriages  there 
has  been  almost  as  much  variety  of  design  as  in  the  other 
branches  we  have  already  noticed.  We  may  say,  however,  that 
the  typical  engine  for  steam  carriages,  as  constructed  in  America, 
is  the  two-cylinder,  double-acting  engine,  reversible  with  the 
Stephenson  link  motion.  The  high  perfection  to  which  these 
engines  have  been  brought  in  America  enables  the  construction 


FIG.  447.  —Crank  Shaft  of  the  "  Locomobile"  Steam  Carriage,  showing  the  cranks  at  both 
ends,  the  ball  bearings  and  eccentrics,  and  the  sprocket  at  the  centre.  Most  steam 
carriage  engines  have  similarly  arranged  crank  shafts,  although  with  several  makes 
the  entire  mechanism  is  turned  from  one  solid  casting. 

of  very  small  motors,  and  the  production  of  a  high  percentage 
of  power.  As  a  usual  thing  such  engines  work  simple,  but  sev- 
eral excellent  types  of  the  American  steam  carriage,  such  as  the 
McKay  and  the  Stearns,  are  equipped  with  compound  engines, 
which,  however,  may  be  run  simple  when  the  extra  power  is 
required,  as,  for  instance,  when  ascending  steep  grades,  or  run- 
ning through  unusually  heavy  roads.  A  few  steam  carriages, 
notably  the  Reading  carriage,  are  also  equipped  with  single- 
acting  multiple  cylinder  engines,  which  combine  peculiarly  in- 
genious devices  for  effecting  reversal  and  controlling  the  valve 

609 


610 


SELF-PROPELLED    VEHICLES. 


SIMPLE  STEAM  ENGINES.  611 

gear.  Single-acting  steam  engines,  with  from  two  to  six  cylin- 
ders, have  also  been  brought  to  high  perfection  in  Europe,  being 
most  familiar  in  the  Gardner-Serpollet  carriages. 


SCIENTIFIC  AMEBICAN, 


FIG.  449.  —Diagram  of  the  "  Locomobile  "  Steam  Carriage,  showing  parts  in  position.  A 
is  the  boiler  shell  of  copper;  a,  the  winding  of  steel  piano  wire;  B,  the  double  cylinder 
engine;  C,  the  adjustable  strut,  or  distance  rod;  D,  the  compensating  gear;  E,  pipe 
leading  from  engine  to  muffler,  F,  for  exhaust  steam;  G,  pipe  leading  from  muffler  to 
vent  at  H;  I,  the  water  supply  tank;  J,  feed  pump  operated  from  the  engine  cross- 
head:  K,  cock  in  front  of  check  valve  on  water  supply  pipe,  for  cutting  off  the  supply 
from  the  tank;  L,  pipe  leading  from  pump  to  the  by-pass,  M;  N,  lever  for  operating 
the  by-pass;  O,  fuel  supply  tank;  P,  reserve  air  tank;  Q,  the  dashboard;  R,  the  air- 
pressure  gauge;  S,  pipe  leading  from  fuel  tank  to  burner,  through  which  gasoline  is 
passed  under  air  pressure;  T.  metal  straps  holding  the  lagging,  U,  around  the  boiler^ 
A;  V,  the  diaphragm  fuel  feed  regulator,  explained  in  connection  with  Fig.  207;  W, 
pipe  leading  steam  from  boiler  to  diaphragm  of  the  regulator;  X,  the  water  glass:  Y. 
the  mirror  for  reflecting  the  water  glass;  Z,  starting  lever.  Other  parts  are:  The 
crank  arm  on  Z  acting  on  the  lever  (1);  the  reversing  lever  (2);  crank  arms  on  the 
reversing  lever  (3  and  4);  the  pop  safety  valve  set  at  240  pounds  (5);  the  steam  pres- 
sure gauge  (6);  fuel  valve  to  main  burner  (7);  foot  pedal  (8)  operating  band  brake 
(9);  wire  wheel  spokes  (10);  pneumatic  tire  (11);  steering  handle  (12);  sprocket  on  rear 
axle  (13);  blow-off  valve  (14);  oil  feed  cup  on  engine  cylinders  (15);  pipe  from  air  tank 

The   "  Locomobile"  Carriage  and  Its  Engine. — One  of  the 

most  efficient  among  the  American  double-acting  simple  engines 
is  that  operating  the  "Locomobile"  steam  carriage,  which  has 
two  cylinders  of  2.\  inches  diameter  by  4-inch  stroke,  and  a  total 


612  SELF-PROPELLED   VEHICLES. 

output  of  4  to  5  horse-power,  at  between  300  and  400  revolu- 
tions per  minute.  It  is  equipped  with  the  Stephenson  link  mo- 
tion and  "D"  slide  valves,  and  operates  the  boiler  pump  from 
the  crosshead.  The  crank  shaft  of  this  engine,  shown  in  the 


FIG,  450.— The  "  Locomobile"  Steam  Carriage  Engine, 

accompanying  drawing,  carries  the  sprocket  at  the  centre,  the 
eccentric  drums  on  either  side,  and  runs  in  enclosed  ball  races, 
with  the  cranks  at  either  extremity.  The  cranks  are  fixed  at 
90  degrees.  As  seen  from  the  accompanying  figure  of  the  en- 


SIMPLE   STEAM  ENGINES. 


613 


gine,  the  cylinder  and  driving  gear  are  hung  on  a  heavy  cast 
frame.  This  frame  is  bolted  to  a  wooden  crosspiece  rigidly  at- 
tached to  the  body  frame  of  the  carriage. 

To  the  base  of  the  frame  is  attached  an  adjustable  strut,  or 
distance  rod,  by  which  its  relative  position,  as  regards  the  rear 
axle,  may  be  varied  by  a  right-and-left  threaded  nut,  or  turn- 
buckle.  By  this  device  the  slack  of  the  chain  may  be  taken  up, 
and,  to  allow  for  the  slight  variation,  thus  necessitated,  the 
steam  pipe  connection  to  the  top  of  the  steam  chest  is  by  a  U-- 
shaped pipe  provided  with  "expansion  joints." 

The  boiler  used  in  this  carriage  has  already  been  described 


AUXILIARY    THROTTLE 


MROTTLC    LEVER 
LEVER    FOR    REVfPStNG 
BV   PASS    LCVC.R 


FIG.  451.  -Plan  Arrangement  of  the  "  Locomobile"  Steam  Carriage,  showing  position  of 
the  parts  indicated  in  Fig.  245. 

in  connection  with  Fig.  144.  It  is  supplied  by  a  small  plunger 
pump  operated  from  the  crosshead  of  the  engine,  drawing  its 
water  from  the  tank  shown  at  the  rear  and  either  side  of  the 
boiler.  On  the  runabout  carriages  of  this  make  the  water  tank 
has  a  capacity  of  fifteen  gallons.  The  water  may  be  cut  off  by 
closing  the  cock,  shown  at  K  in  the  lettered  diagram  of  this 
carriage,  or  may  be  returned  to  the  tank  by  opening  the  by-pass 
valve,  M,  by  the  lever,  N,  at  the  driver's  right  hand.  Up  to  the 
present  time  the  manufacturers  of  this  carriage  have  avoided 
the  use  of  most  automatic  devices,  other  than  the  fuel  regulator, 
as  already  described. 


CHAPTER    FORTY-ONE. 
SINGLE-ACTING   STEAM   CARRIAGE   ENGINES. 

The  Serpollet  Single-Acting  Engines. — In  the  effort  to  sim- 
plify, as  far  as  possible,  the  construction  and  operation  of  steam 
vehicle  motors,  intended  for  use  on  light  carriages,  several  in- 
ventors have  contrived  excellent  types  of  single-acting  engines. 
Among  the  advantages  to  be  derived  from  the  use  of  this  type 
of  motor,  we  may  mention  dispensing  with  the  stuffing-box  and 
several  other  constructions,  which  involves  constant  danger  of 
wear  and  difficulty  of  repair.  Among  the  best  known  single- 
acting  steam  engines  may  be  mentioned  those  designed  by  Leon 
Serpollet,  and  used  on  the  steam  carriages  manufactured  by  his 
firm.  As  constructed  by  him,  the  single-acting,  steam  engine 


FlO.  452.  — Gardner-Serpollet  Steam  Carriage  built  for  King  Edward  VII.    This  carriage 
fairly  represents  the  designs  of  Serpollet. 

very  much  resembles  some  types  of  gasoline  motors  used  on 
heavy  vehicles,  both  as  regards  the  cylinder  and  piston  and  oper- 
ation of  the  valves.  In  an  accompanying  figure  is  shown  an 
elevation,  partly  in  section,  of  one  of  his  horizontal  double  op- 
posed cylinder  engines.  As  may  be  seen  there,  the  cylinders  are 
open  at  the  forward  end,  toward  the  crank  space,  in  a  manner 
very  similar  to  that  used  on  gasoline  motors  of  the  same  pat- 
tern. The  piston  is  of  the  trunk  type,  consisting  of  a  somewhat 
elongated  hollow  cylinder,  with  the  crank  rod  pivoted  on  the 
gudgeon  pin  somewhat  less  than  midway  in  its  length.  The 


SINGLE-ACTING   STEAM  ENGINES. 


615 


valves  in  this  engine  are  of  the  familiar  mushroom  or  poppet 
type,  and  are  opened  by  a  push  rod  positively  operated  from  a 
cam  shaft.  This  shaft  is  operated  by  a  spur-wheel,  which  meshes 
with  another  spur  of  the  same  diameter,  mounted  on  the  crank- 
shaft, so  that  the  two  turn  in  even  rotation.  The  exhaust  valves 
are  of  precisely  similar  construction  and  are  also  positively  oper- 
ated from  the  same  cam-shaft. 

Such  an  engine  as  this  has  been  constructed  with  from  two  to 
six  cylinders,  and  as  may  be  understood,  gives  about  the  same 


FIG.  453.-One  Model  of  Serpollet  Single-acting  Two-cylinder  Engine.  As  may  be  seen, 
this  engine,  with  cam-actuated  poppet  valves,  centrifugal  governor  for  regulating  the 
cam  movement,  and  large  fly  wheel,  closely  resembles  gas  engines  of  the  double-op- 
posed cylinder  type. 

power  effect  as  an  engine  of  the  ordinary  design  and  same  pro- 
portions of  stroke,  having  from  one  to  three  cylinders.  The  Cyl- 
inders operate  on  one  plane,  and  are  not  offset,  as  in  many  op 
posed-cylinder  gasoline  motors,  the  danger  of  interference  of 
the  crank  rods  being  prevented  by  constructing  each  of  them 
to  embrace  only  about  one-third  the  circumference  of  the  crank- 
pin,  thus  permitting  a  sufficient  play  to  enable  them  to  adapt 
their  motion  to  the  full  dip  of  the  crank.  The  crank  ends  of 
these  rods  are  held  in  place  by  clamp  brasses  at  either  side.  In 


616  SELF-PROPELLED   VEHICLES 

a  diagonally  arranged  motor  of  the  same  description,  the  same 
end  of  non-interference  is  attained  by  forking  the  crank  end  of 
one  of  the  crank-rods,  and  constructing  the  other  single,  so  that 
the  former  may  work  over  the  latter  on  the  crank-pin.  As  may 
be  understood  from  the  fact  that  the  steam  and  exhaust  valves 
are  positively  operated  by  a  series  of  cams  on  a  shaft,  so  that 
when  the  steam  valve  of  one  is  open,  its  exhaust  is  closed,  in- 
volving that  the  steam  valve  of  the  opposite  cylinder  is  closed 
and  its  exhaust  open.  In  order  therefore  to  reverse  the  engine, 
it  is  necessary  only  to  slide  the  row  of  cams  on  the  square  cam- 
shaft that  carries  them,  so  as  to  shift  the  positions  and  operation 
of  the  valves  on  the  two  cylinders. 

All  the  Serpollet  carriage  engines  of  this  description  are  sup- 
plied by  the  Serpollet  flash  generator,  already  described,  the  fuel 
and  water  being  fed  and  regulated  by  a  system  of  pumps  and 
valves,  already  described.  For  driving  an  ordinary  road  carriage, 
seating  two  passengers,  a  two-cylinder  motor  is  used,  with  a 
stroke  and  diameter  each  equal  to  about  2.55  inches,  giving, 
with  700  revolutions  a  minute  and  a  mean  effective  pressure  of 
about  75  pounds,  an  approximate  rating  of  3  horse-power. 


CHAPTER    FORTY-TWO. 
COMPOUND   STEAM    ENGINES. 

Compound  Steam  Engines  for  Light  Carriages. — Although 
many  of  the  earliest  types  of  the  American  steam  carriage  still 
use  simple  engines,  several  of  the  most  excellent  of  the  later  pat- 
terns have  adopted  compound  engines.  The  principal  objection 
made  by  many  authorities  to  the  use  of  compound  engines  on 
steam  road  carriages  of  light  weight  is  that  with  cylinders  of 
average  dimensions,  working  power  of  between  150  and  200 
pounds,  in  the  high  pressure  cylinder,  and  a  cut-off  generally 
between  \  and  f  stroke,  which  has  been  found  most  economical 
under  ordinary  conditions,  the  low  pressure  cylinder  would  be 
doing  little  or  no  work,  the  whole  strain  of  operation  coming  on 
the  former,  which  would  practically  be  working  against  a 
vacuum.  On  the  other  hand,  with  the  final  pressure  of  between 
35  and  40  pounds,  and  the  port  clearances  necessarily  amount- 
ing to  between  20  and  30  per  cent.,  there  is  a  considerable  waste 
of  steam,  as  well  as  excessive  condensation.  A  well-known 
manufacturer  of  steam  carriage  engines  states,  that  in  order  to 
obtain  effective  work  from  both  cylinders  of  a  compound  en- 
gine, the  high  pressure  cylinder  must  be  made  about  one-half 
the  size  of  the  cylinder  used  in  the  simple  engine.  Then,  he  as- 
serts, the  mean  pressure  will  range  from  75  to  100  pounds  in  the 
usual  running,  with  cut-off  at  f  stroke  and  the  diameters  of  the 
two  cylinders  in  ratio  of  I  to  3,  and  the  low  pressure  cylinder  will 
do  its  share  of  the  work,  with  the  desired  economy  of  power. 
The  difficulty  claimed  with  this  arrangement  is,  that  the  total 
reserve  power  will  then  be  only  about  one-half  that  of  the  sim- 
ple engine,  unless  boiler  steam  can  be  admitted  to  both  cylin- 
ders at  any  desired  time  while  running,  as  well  as  in  starting,  and 
the  back-pressure  be  eliminated  by  exhausting  from  both  to  at- 
mosphere. 

Another  objection  is  that  the  efficient  compound  engines  used 
in  stationary  power  plants,  on  ships,  and,  to  a  certain  extent  in 
railroad  locomotives,  are  operating  constantly  against  a  practi- 
cally fixed  load,  which  is  not  the  case  in  steam  carriage  work/ 

617 


618 


SELF-PROPELLED    VEHICLES. 


COMPOUND   STEAM  ENGINES.  619 

But  this  is  not  of  such  vital  importance,  since  the  average  run  of 
compound  engines,  designed  for  light  road  carriage  use,  may  be 
run  simple,  whenever  it  is  so  desired,  and  the  power  may  be 
varied  with  any  well-made  simple  engine  by  shifting  the  point 
of  cut-off.  Thus,  as  is  admitted  by  most  experienced  steam-car- 
riage drivers,  the  throttle  valve  must  be  very  constantly  manipu- 
lated, in  order  to  maintain  anything  like  uniform  speed  on  ordi- 
nary roads,  whose  surface  conditions  are  ever  changing.  One 
important  consideration,  however,  is  that  a  compound  engine, 
with  two  cylinders  of  different  dimensions,  involves  considerable 
vibration,  and  consequent  strain  on  the  parts,  such  as  is  not  ex- 
perienced with  a  simple  engine,  whose  cylinders  are  uniform  as 
to  size  and  power-output.  Thus,  when  running  compound,  the 
small  cylinder  is  exerting  a  power  somewhat  in  excess  of  the 
larger  one,  and,  when  both  are  running  with  live  steam,  the 
larger  one  is  powered  two  or  three  times  higher  than  the  smaller. 
Such  an  objection  undoubtedly  holds  good  for  a  given  type  of 
engine,  but  with  the  better  designed  American  road  carriages, 
equipped  with  compound  engines,  the  vibration  seems  hardly 
more  noticeable  than  with  the  easy-moving  simple  engine. 

The  Stearns  Compound  Engine. — The  compound  engine 
used  on  the  Stearns  steam  carriage  is  one  of  the  most  typical 
and  efficient  of  its  class.  The  high  pressure  cylinder* 
is  2j  inches  in  diameter,  by  3^  inch  stroke,  and  the  low 
pressure  cylinder  3  inches  in  diameter,  by  3^  inch  stroke. 
As  is  claimed,  each  develops  2f  horse-power  when  running 
compound,  and  about  double  that  when  running  simple.  As 
shown  in  the  accompanying  diagram,  it  is  built  on  the  usual  plan 
of  the  double-cylinder  steam  carriage  engine,  each  cylinder  be- 
ing controlled  by  piston  valves  of  the  usual  construction.  The 
valve  chest  also  contains  inserts  or  liners,  which  increase  the 
accuracy  of  the  parts  and  admit  of  ready  adjustment  when  the 
old  liners  are  worn  by  use.  Between  the  two  valve  chests  and 
in  connection  with  both,  is  the  controller  valve  chamber,  which 
also  contains  a  piston  valve,  similar  to  that  used  in  connection 
with  the  cylinders,  except  that  it  is  larger  in  diameter  and  has 
double  connections.  The  position  of  this  control  valve  may  be 
altered  by  a  lever  coming  to  the  hand  of  the  driver,  so  that  at 
any  time  the  operation  of  the  engine  may  be  shifted  from  sim- 


620  SELF-PROPELLED    VEHICLES. 

pie  to  compound  or  from  compound  to  simple.  This  control 
valve  is  bored  from  end  to  end,  and  has  the  usual  angular  re- 
cess on  its  outer  surface,  besides  the  internal  port  extending 
clear  around  the  top,  bringing  into  connection  various  passages 
leading  from  the  control  valve  chest  to  the  high  and  the  low- 
pressure  valve  chests  and  their  exhaust  ports.  As  shown  in  the 
illustration,  the  control  valve  stands  at  a  point  just  above  the 
ports  which  cut  off  the  steam  from  the  steam  chests.  Were  it 
lowered,  so  that  its  top  would  be  even  with  the  bottom  port  on 
the  high  pressure  cylinder  side,  the  engine  would  run  com- 


Fio.  455.  —Compound  Engine  of  the  Stearns  Steam  Carriage 

pound.  In  this  position,  therefore,  the  live  steam  from  the  boiler 
passes  from  the  control  valve  chest  through  the  port  just  cleared 
by  the  control  valve,  to  the  high  pressure  steam  chest,  being 
then  distributed  by  the  high  pressure  valve,  as  it  alternates  be- 
tween the  two  ends  of  the  cylinder.  The  high  pressure  valve 
being  shown  in  a  position  where  the  lower  end  of  the  high  press- 
ure cylinder  exhausts,  the  path  of  the  steam  leaving  this  end  of  the 
cylinder  may  be  easily  followed  to  the  steam  valve,  through  the 
exhaust  passage,  and  the  high  pressure  valve  through  the  pas- 
sage leading  to  the  control  valve  chest.  Thence,  through  the 


COMPOUND   STEAM  ENGINES. 


621 


internal  port  of  the  control  valve,  and  through  another  passage 
leading  to  the  low  pressure  valve  chest,  it  is  distributed  alter- 
nately to  both  ends  of  the  low  pressure  cylinder.  As  the  high  press- 
ure piston  is  shown  at  one-half  stroke,  and  as  the  two  cranks  are 


FIG.  456.  —Section  of  the  Stearns  Compound  Steam  Carriage  Engine.  A  is  the  high-press- 
ure cylinder;  B,  the  low-pressure  cylinder;  C  and  D,  the  steam  valves  operated  by 
single  eccentrics;  E,  the  central  control  valve  and  chamber. 

set  at  90  degrees,  the  low  pressure  piston  is  in  its  extreme  inner 
position,  and  the  lower  end  of  the  cylinder  is  just  beginning  to 
exhaust.  The  steam  exhausted  from  the  low  pressure  cylinder 
flows  through  the  port  to  the  exhaust  chamber  surrounding  the 


SELF-PROPELLED   VEHICLES. 

low  pressure  valve,  and  from  there  through  the  passage  to  the 
exhaust  chamber  surrounding  the  control  valve,  whence  it  is 
led  to  atmosphere. 

If  the  control  valve  be  raised  until  the  passage  shown  in  the 
drawing,  as  connecting  the  exhaust  port  of  the  high  pressure 
cylinder  with  the  internal  port  of  the  control  valve,  be  uncovered, 
the  operations  of  the  exhaust  and  admission  ports  are  reversed 
and  the  engine  runs  in  the  reverse  direction.  When  the  control 
valve  is  shifted  until  it  uncovers  the  passage  shown  in  the  draw- 
ing, as  connecting  its  internal  port  with  the  low  pressure  valve 
chest,  live  steam  from  the  boiler  will  flow  to  both  valve  chests, 
and  the  engine  will  then  work  simple,  thus  providing  increased 
power  that  may  be  required  in  an  emergency,  as  when  ascending 
a  steep  incline  or  passing  over  an  unusually  rough  road.  Fur- 
ther, by  slightly  varying  the  position  of  the  control  valve,  the 
steam  may  also  be  throttled  by  this  manner  of  working  the  en- 
gine. The  exhaust  ports  of  both  high  and  low  pressure  cylinders 
being  then  in  communication  with  the  central  exhaust  port,  both 
will,  therefore,  exhaust  to  atmosphere.  As  shown  in  practice, 
these  simple  acts  of  shifting  the  control  valve,  may  be  readily  and 
rapidly  acquired,  thus  enabling  the  operator  to  economize  both 
fuel  and  water  by  regulating  the  power  output  to  the  require- 
ments of  travel.  Its  practical  operation  also  demonstrates,  when 
running  simple,  that  the  average  American  steam  carriage  is 
somewhat  over-powered  for  the  requirements  of  good  roads  and 
average  speed,  and  that  a  large  percentage  of  the  steam,  ordi- 
narily wasted,  may  be  used  for  effective  work. 

The  Thornycroft  Road  Wagon  and  Compound  Engine. — The 

practice  of  using  compound  engines  on  motor  road  carriages 
has  been  much  more  frequently  adopted  on  heavy  wagons  and 
lorries  than  on  light  pleasure  carriages.  One  of  the  best  known 
makes  of  motor  road  wagons  using  compound  engines  is  the 
Thornycroft,  several  parts  of  which  have  already  been  described. 
The  engine  used  on  the  two  and  four  ton  wagons,  manufactured 
under  the  Thornycroft  patents  in  England  and  America,  is  a 
two-cylinder  horizontal  compound  engine,  having  a  4  inch  di- 
ameter for  the  high  pressure  cylinder  and  a  7  inch  diameter  for 
the  low  pressure,  and  a  stroke  of  5  inches.  The  steam  valves 
are  of  the  balanced  cylindrical  type  and  are  operated  by  single 


COMPOUND   STEAM  ENGINES. 


623 


624 


SELF-PROPELLED   VEHICLES. 


COMPOUND   STEAM  ENGINES. 


625 


eccentric  gear  from  the  crank  shaft.  As  shown  in  the  sectional 
drawing  of  this  engine,  the  eccentric  carries  an  arm,  C,  which  is 
connected  to  the  valve  rod  by  a  link  bar.  It  is  also  connected  to 
the  swinging  link,  A  B,  by  which  reversal  may  be  effected. 
When  this  swinging  link  is  in  the  position  shown  in  the  drawing, 
the  wagon  moves  straight  ahead ;  when  it  is  brought  downward, 
to  the  position  marked  "astern,"  the  direction  is  reversed.  The 
intermediate  point,  of  course,  has  no  effect  on  the  movement  of 
the  valve.  This  device  furnishes  a  simple  and  ready  method  of 
controlling  the  engine,  and  has  the  advantage  of  being  less  com- 
plicated than  the  ordinary  link  motion.  An  engine  of  the  dimen- 
sions specified  above  can  develop  20  brake  horse-power  at  440 


Fio.  459.— Change  Speed  Gear  used  on  the  Thornycroft  Steam  Wagon. 

revolutions  and  35  brake  horse-power  at  770  revolutions,  when 
the  low  speed  gear  is  in  use.  This  is  an  exceptionally  high  rat- 
ing for  an  engine  of  this  size ;  measuring  only  3^x2^x1^  feet, 
and  weighing  less  than  500  pounds. 

Contrary  to  the  usual  practice  with  steam  road  wagons,  both 
light  and  heavy,  the  Thornycroft  wagon  has  a  system  of  change 
speed  gears,  somewhat  on  the  pattern  of  those  used  in  connec- 
tion with  gasoline  motors.  As  shown  in  an  accompanying  fig- 
ure, these  gears,  mounted  on  a  counter-shaft,  may  be  changed 
by  shifting  in  the  width  of  the  wagon  by  means  of  a  lever,  5\ 
When  this  lever  is  in  the  position  indicated,  the  low  speed  gears, 
M  and  N,  are  meshed.  When,  however,  it  is  moved  to  the  right, 
as  indicated  by  the  dotted  lines,  the  bearings,  E  and  E,  are  also 
shifted  as  shown,  bringing  the  gears,  K  and  L,  into  engagement. 


626 


SELF-PROPELLED  VEHICLES. 


FIG.  480.— The  "  Lifu"  Compound  Steam  Engine  for  heavy  vehicle  use.  This  section  is 
drawn  through  the  centre  of  the  cylindrical  steam  chests,  which,  as  in  the  Thorny- 
croft  engine  (Fig.  273),  are  below  and  at  the  sides  of  the  steam  cylinders.  The  appear- 
ance of  eccentricity  in  the  attachment  of  the  piston  rods  may  tnus  be  understood. 


COMPOUND   STEAM  ENGINES.  627 

This  gives  the  high  speed  forward.  The  operation  of  the 
wheels,  which  are  hung  on  a  loose  rotating  rear  axle,  as  already 
explained  on  page  104,  in  connection  with  Figs.  89  and  90,  af- 
fords an  exceedingly  elastic  connection,  and  great  tractive  ef- 
ficiency. The  elevation  of  the  wagon,  showing  the  relative  ar- 
rangement of  the  parts,  is  shown  in  an  accompanying  figure. 
The  -plan  is  given  in  Fig.  73  and  a  description  of  the  water  tube 
boiler  on  pages  190-193. 

The  "Lifu"  Compound  Steam  Engine. — The  compound  steam 
engine  used  on  the  "Lifu"  steam  wagons  is  shown  in  section  in 
an  accompanying  figure.  It  is  of  the  cross-compound  horizon- 
tal type,  with  reversing  links,  having  cylinders  of  3  inch  and  6 
inch  diameters  respectively,  and  a  5  inch  stroke.  The  steam  in- 
let of  both  cylinders  is  controlled  by  simple  balanced  piston 
valves,  and  as  indicated  in  the  drawing,  the  valve  boxes  are 
placed  somewhat  below  the  general  level  of  the  engine.  When 
running  compound  the  steam  is  exhausted  from  the  high  press- 
ure cylinder  into  a  receiver  tube,  which,  as  shown  by  dotted  lines 
in  the  drawing,  connects  the  two  cylinders  and  their  valve  boxes 
from  below.  There  is  also  an  auxiliary  valve  as  shown  at  the 
right  hand  of  the  low-pressure  cylinder,  by  which  live  steam 
from  the  boiler  may  be  admitted  direct  to  the  low-pressure  cyl- 
inder, thus  permitting  both  to  run  simple  whenever  occasion  de- 
mands. 

Among  the  special  features  of  this  engine  may  be  mentioned  a 
second  pair  of  gland  boxes  run  between  the  forward  cylinder 
head  and  the  guide  bars,  in  order  to  prevent  all  leakage  of  con- 
densed steam  into  the  crank  case,  which  is  enclosed  so  as  to  al- 
low the  moving  parts  to  run  in  oil.  The  main  feed  pump  is 
worked  from  the  crank-shaft,  being  geared  direct  to  a  single 
eccentric,  which  works  on  a  small  secondary  shaft  operated  from 
the  main  shaft  by  spur-wheels.  Attached  to  the  strap  of  this 
single  eccentric  is  a  forked  connecting  rod  which  works  on  a 
crosshead  attached  to  the  rear  of  the  pump.  By  this  arrange- 
ment it  is  possible  to  reduce  the  speed  of  the  pump,  since  the 
ratio  of  the  two  meshed  spur-wheels  is  about  I  to  6.  In  addition 
to  this  pump,  there  is  also  an  independent  steam  pump  for  use  in 
case  of  emergency. 


SELF-PROPELLED    VEHICLES. 


The  White  Engine  and  Carriage. — Although  the  gasoline 
carriage  seems  to  have  supplanted  the  steamer  in  a  large  num- 
ber of  cases,  a  very  desultory  survey  of  the  field  will  readily 
prove  that  this  result  has  occurred  only  because  very  many  of 
the  steam  carriages  of  two  or  three  years  ago  were  not  perfectly 
calculated  for  the  unskilled  drivers  who  must  use  them. 


FIG.  461.— The  White  Compound  Steam  Engine.  The  cylinders  are  encased  in 
an  aluminum  jacket  filled  with  asbestos  lagging.  The  crank  case  and  all 
parts  which  do  not  bear  a  working  strain  are  of  aluminum.  The  diaphragm 
regulator  which  acts  upon  the  by-pat>s  valve  is  shown  to  the  left,  below  the 
cylinder;  also  the  water  pump,  engaged  to  the  cross-head  pin.  The  water 
pumps  are  of  very  short  stroke  and  all  are  liberally  proportioned.  The  rocker 
arm  on  the  top  of  the  cylinders  operates  the  simpling  device  whereby  the 
low  cylinder  receives  high-pressure  steam. 

The  ideal  conditions  are  undoubtedly  found  in  the  flash  gen- 
erator, which,  as  has  already  been  remarked,  furnished  the 
first  impulse  for  the  practical  modern  steam  carriage.  Be- 
cause a  flash  generator  should  be  no  more  real  trouble  to  man- 
age than  the  carburetter  of  a  gasoline  engine,  the  greatest  draw- 


COMPOUND  STEAM  ENGINES.  629 

back  of  the  steamer  is  eliminated  and  the  internal-combustion 
motor  is  fairly  rivaled  by  the  older  form  of  heat  engine. 

All  these  advantages  seem  to  be  embodied  in  the  later  models 
of  the  White  steamer,  which  are  all  built  on  the  lines  of  gasoline 
touring  cars,  having  the  compound  engine  at  the  front  of  the 
body,  under  a  bonnet  and  driving  direct,  by  propeller  shaft  and 
bevel  gear  connections  to  the  rear  axle.  The  flash  generator, 
thermostat  regulator  and  burner  used  on  this  carriage  have 
already  been  described  in  previous  chapters.  The  engine  is  a 
double-cylinder  compound,  the  bores  being  3  and  5  inches  re- 
spectively, and  the  stroke  3^  inches,  the  low-pressure  cylinder 
being  set  foremost. 

An  enclosed  crank  case  protects  the  working  parts  from  dust 
and  permits  the  splash  system  of  lubrication  to  be  used.  The 
cra,nk  shaft  is  built  up  under  hydraulic  pressure,  and  balls  are 
used  in  all  the  shaft,  crank  pin  and  eccentric  bearings.  The  valve 
motion  is  of  Stephenson  link  type,  centrally  hung,  and  between 
the  two  pairs  of  valve  eccentrics  is  a  fifth  eccentric  which  oper- 
ates, through  a  rocking  arm,  the  double-ended  plunger  of  the 
feed  pump  and  the  condenser  pump  seen  on  the  left  side  of  the 
engine.  Connected  directly  to  the  upper  or  feed  pump  is  the 
diaphragm  regulator,  which  governs  the  by-pass  valve.  When 
this  valve  is  open  the  water  passing  through  the  pump  returns 
by  a  short  bent  pipe  directly  back  to  the  bottom  of  the  pump,  and 
so  circulates  continuously  until  the  by-pass  valve  is  closed. 

For  starting,  or  for  occasions  where  a  strong  pull  is  desired, 
steam  may  be  admitted  directly  to  the  low-pressure  cylinder. 
This  is  done  by  pressing  a  foot  plunger  marked  "Start,"  which 
operates  the  simpling  device  actuated  through  the  rock  shaft 
mounted  on  top  of  the  engine. 

From  the  engine  the  exhaust  steam  proceeds  to  the  condenser 
at  the  front  of  the  bonnet,  then  through  the  separator,  where  the 
cylinder  oil  is  removed,  to  the  tank. 

A  peculiar  advantage  of  the  flash  system  of  generating  steam 
is  that,  contrary  to  all  experience  with  fire-tube  boilers,  no  in- 
crustation or  sediment  can  lodge  in  the  coils,  owing  tp  the  rapid- 
ity of  the  circulation.  The  value  of  this  in  a  country  where  only 
hard  water  can  be  had  cannot  be  overestimated. 


CHAPTER    FORTY-THREE. 

HINTS     ON      THE     CARE     AND     OPERATION      OF      A      GASOLINE 
VEHICLE. 

Water  and  Gasoline  Supply. — The  first  consideration  pre- 
vious to  starting  a  motor  carriage  is  to  see  that  the  water  and 
gasoline  tanks  are  properly  filled ;  indeed,  it  is  a  good  practice  to 
make  it  a  habit  to  test  both  tanks  on  each  occasion  of  preparing 
for  a  run.  Some  motor  carriages  have  glass  gauge  tubes  fixed 
to  the  fuel  and  water  tanks,  so  that  the  level  of  the  liquids  in 
both  cases  may  be  determined  at  a  glance.  In  others  it  is  a  simple 
matter  to  test  the  level  by  inserting  a  stick  in  the  filling  hole  and 
noting  the  height  to  which  the  liquid  rises  on  it.  This  may  be 
done  with  gasoline  if  the  stick  is  withdrawn  quickly  and  ex- 
amined before  evaporation  takes  place. 

General  Directions  for  Starting  the  Motor. — When  all  rea- 
sonable preparations  have  been  made,  and  it  is  evident  that  the 
motor  and  running  parts  are  in  working  order,  the  next  im- 
portant step  is  to  open  the  cock  leading  from  the  gasoline  tank 
to  the  carburetter,  and  also  to  close  the  sparking  circuit  by  means 
of  the  designated  switch,  or  plug,  provided  for  that  purpose.  The 
spark  should  be  set  back  to  the  full  length  of  the  quadrant. 

Failure  of  the  Motor  to  Operate. — In  a  large  number  of  cases 
when  the  motor  fails  to  start,  or  stops  or  slows  down  from  no 
other  assignable  cause,  it  is  probable  that  the  trouble  lies  in 
some  disarrangement  of  the  electrical  sparking  circuit  or  attach- 
ments. If  a  jump-spark  is  used,  it  is  probable  that  the  plug  has 
become  short-circuited  through  either  a  deposit  of  carbonized 
particles  between  the  sparking  points,  which  defect  frequently 
follows  the  use  of  too  rich  a  fuel  mixture,  or  else  that  the  insula- 
tion has  been  broken  down  and  that  a  path  is  provided  for  the 
electrical  current  between  the  two  conducting  portions  of  the 
plug.  If  the  former  defect  has  occurred,  the  sparking  plug  may 
be  unscrewed  from  the  combustion  chamber  and  the  condition 


GASOLINE  VEHICLE   OPERATION.  631 

may  be  readily  detected.  This  carbon  deposit  may  be  readily  re- 
moved by  rubbing  the  points  with  a  piece  of  light  emery  paper 
until  the  bright  surface  of  the  metal  is  again  visible.  Care  should 
be  taken,  however,  by  non-practiced  hands,  lest  the  metal  be  un- 
duly worn  in  the  operation.  The  sparking  points  of  a  jump-spark 
plug  should  always  be  mounted  at  a  fixed  distance  of  not  more 
than  one  twenty-fifth  of  an  inch,  which  is  approximately  equal  to 
the  thickness  of  an  average  heavy  business  card.  If,  on  the  other 
hand,  the  plug  has  become  disabled  by  a  short-circuit  through 
the  body  below  the  sparking  points,  it  is  practically  useless,  and 
it  is  unnecessary  for  the  driver  to  attempt  to  repair  the  injury. 
The  reason  of  this  is  that  such  a  condition  of  short-circuiting 
is  due  to  the  fact  that  the  insulation  has  been  burned  out,  or  that 
foreign  substances  have  been  deposited  in  such  a  manner  as  to 
leave  a  path  for  the  electrical  current. 

Failure  of  the  engine  to  operate  properly  may  be  readily 
traced  to  the  sparking  circuit  by  unscrewing  the  tap  of  the  peep- 
hole, or  the  disconnecting  inlet  valve  case,  according  to  the  kind 
of  motor  that  is  used,  and  observing  the  intensity  and  quality 
of  the  spark,  if  any  occurs,  by  continuing  to  turn  the  crank  used 
for  starting  the  motor. 

Troubles  with  the  Ignition  Circuit. — Troubles  with  the  ig- 
nition circuit,  however,  may  be  due  to  derangements  at  some 
point  otjier  than  the  sparking  plug,  and  before  removing  the  plug 
and  substituting  a  new  one  it  is  desirable  to  see  that  all  the  other 
parts  of  the  circuit  are  in  proper  working  condition.  Among 
other  things  that  should  be  carefully  provided  for,  the  driver 
should  see  that :  (i)  Insulation  of  the  lead  wires  is  perfect  at  all 
points  and  that  short-circuiting  does  not  occur  through  contact 
with  any  of  the  metal  parts  of  the  vehicle  or  motor ;  (2)  the  ter- 
minals of  all  lead  wires  should  be  tightly  screwed  under  binding 
post ;  (3)  the  contact-breaking  trembler  should  be  adjusted  so  as 
to  operate  properly,  which  means  that  all  screws  and  attachments 
should  be  kept  securely  tight;  (4)  the  battery  should  be  tested 
occasionally  in  order  to  ascertain  whether  it  is  giving  the  full 
amount  of  current.  Most  of  the  chemical  batteries  used  in  the 
sparking  gas  engines  may  be  relied  upon  to  give  the  required 
current  for  a  certain  definite  period ;  therefore,  unless  some  de- 
fect in  circuit  has  caused  unusual  waste  of  electrical  energy,  or 


SELF-PROPELLED    VEHICLES. 

an  unusually  long  continued  operation  of  the  vehicle  has  practi- 
cally exhausted  it  for  the  time  being,  it  is  safe  to  conclude  that 
the  trouble  is  at  some  other  point.  A  battery  may  be  easily  tested 
by  the  use  of  the  ordinary  pocket  gauge,  which  may  be  obtained 
from  any  electrical  supply  house,  and  when  it  is  desired  to  make  a 
test  the  gauge  may  be  readily  connected  to  the  terminals  of  the 
battery  and  will  register  the  output  with  sufficient  accuracy  for 
all  practical  purposes.  In  making  such  a  test,  however,  it  is  de- 
sirable to  continue  it  no  longer  than  is  absolutely  necessary  to 
read  the  gauge  record,  since  the  operation  means  a  short-circuit- 
ing of  the  battery,  which  will  prove  fatal  to  any  chemical  cell  if 
long  continued.  Where  chemical  cells  are  used,  it  is  a  compara- 
tively simple  matter  to  carry  several  extra  cells  in  the  vehicle  in 
order  to  be  able  to  make  substitution  in  case  of  suspected  diffi- 
culty with  the  battery. 

Starting  the  Carriage. — When  the  motor  is  running  properly 
and  the  driver  wishes  to  start  the  carriage,  the  first  operation  is 
to  throw  on  the  clutch  with  the  speed  adjusted  to  low  gear;  this 
is  very  essential  in  order  that  the  start  should  not  be  too  sudden, 
which  would  result  in  discomfort  to  the  occupants  of  the  car- 
riage and  strain  on  the  parts.  After  the  carriage  has  once  fairly 
started,  the  second  speed  may  be  thrown  in  as  soon  as  desired. 
It  is  very  essential,  however,  particularly  for  an  unskilled  driver, 
to  recognize  the  fact  that  with  any  variety  of  change  speed  gear- 
ing, the  changing  of  speed  ratios  must  always  be  preceded  by 
throwing  out  the  main  clutch.  In  changing  from  a  lower  to  a 
higher  speed,  it  is  important  that  the  operation  should  be  per- 
formed on  as  level  a  roadway  as  possible  and  should  be  consum- 
mated before  the  carriage  has  lost  its  momentum.  On  the  other 
hand,  in  changing  from  a  high  speed  to  a  lower  one,  it  is  ex- 
ceedingly desirable,  if  not  imperative,  that  the  momentum  of  the 
carriage  should  be  allowed  to  fall  as  near  as  possible  to  the  de- 
sired speed  before  the  new  gear  is  thrown  in.  Hill-climbing  is 
invariably  performed  with  a  low  gear,  but  it  is  well  to  observe 
the  rule  that  the  higher  speed  should  be  used  until  the  travel  of 
the  carriage  has  fallen  considerably,  and  the  motor  shows  sierns 
of  laboring;  it  is  then  the  time  to  throw  in  the  low  speed,  which 
relieves  the  motor  of  any  undue  strain,  and  enables  the  hill  to  be 
climbed  without  injury  to  the  moving  parts. 


GASOLINE  VEHICLE   OPERATION.  633 

Working  the  Carriage  on  Down  Grades. — In  descending 
grades  many  drivers  indulge  in  the  sport  of  coasting,  which  is 
very  delightful,  but  somewhat  dangerous  with  heavy-weight  cars, 
and  an  inexperienced  driver  should  be  particularly  careful  in  per- 
forming this  feat,  since  it  has  frequently  happened  that  a  heavy 
car  has  become  unmanageable  on  a  steep  grade,  the  steering  ap- 
paratus failing  to  act,  with  the  result  that  a  serious  accident  oc- 
curs. In  coasting  the  clutch  is  thrown  out  and  the  carriage  al- 
lowed to  move  down  the  grade  under  its  own  momentum.  With 
carriages  having  a  direct  spur  drive  to  the  rear  axle,  like  the  light 
De  Dions  and  some  early  American-made  light  phaetons,  it  is 
possible  to  leave  the  motor  in  gear  with  the  driving  connections 
and  by  interrupting  the  sparking  circuit,  allow  it  to  act  as  a  buffing 
brake  to  maintain  the  speed  within  safe  limits.  In  coasting  down 
a  hill  a  driver  should  always  observe  the  precaution  of  keeping  his 
foot  or  hand,  as  the  case  may  be,  on  the  connections  of  the  brak- 
ing lever,  in  order  that  the  speed  of  the  carriage  may  be  checked 
at  any  desired  point.  It  is  always  well  to  keep  the  hand  on  the 
braking  connections  in  any  such  position,  until  sufficient  experi- 
ence in  running  the  carriage  has  been  obtained  to  enable  risks 
to  be  incurred  with  impunity. 

In  descending  a  very  steep  grade  the  operator  should  never 
allow  his  vehicle  to  attain  a  high  speed.  If  the  motor  is  left  in 
gear  with  the  sparking  circuit  interrupted,  as  already  mentioned, 
the  low  gear  of  the  speed  changer  should  be  used,  but  the  retard- 
ing effect  of  the  piston  compression  should  be  assisted  by  slight 
pressure  upon  the  emergency  brakes.  If  the  brakes  fail  to  work 
properly,  in  order  to  restrain  the  speed  before  it  reaches  an  un- 
manageable point,  the  high  gear  should  be  thrown  in,  which  will 
materially  assist  the  effort  of  the  brakes,  unless  the  latter  are 
completely  disabled. 

Turning  Corners  and  Side  Slipping.— There  are  several 
other  conditions  met  with  in  ordinary  travel  which  should  be 
rigidly  observed.  The  first  of  these  relates  to  the  necessary  op- 
erations performed  in  turning  corners.  Any  turns,  except  those 
of  the  longest  radius,  should  be  made  on  low  gear.  If  a  sudden 
turn  is  to  be  made,  as  in  rounding  a  street  corner,  the  best  prac- 
tice, when  moving  at  a  high  speed  straight  ahead,  is  either  to 
throw  out  the  main  clutch  and  allow  the  vehicle  to  turn  with  its 


634-  SELF-PROPELLED    VEHICLES. 

own  momentum,  or  to  retard  the  spark  by  means  of  the  properly 
designated  connections  to  hand,  in  order  that  the  carriage  may 
not  race  around  the  corner,  with  the  very  probable  result  of  in- 
curring injury  or  accident,  particularly  on  a  wet  or  greasy  street, 
where  the  wheels  are  liable  to  slip  sideways,  when  turning  at  the 
high  speed,  with  the  result  in  frequent  instances  of  seriously 
damaging  the  running  gear.  Also,  if  too  short  a  turn  is  made, 
the  carriage  will  have  a  tendency  to  swing  bodily,  and  may  even 
go  so  far  as  to  turn  completely  around  in  an  opposite  direction. 
This  will  not,  however,  cause  a  well-built  vehicle  to  capsize, 
owing  to  the  properly  adjusted  centre  of  gravity,  but,  particu- 
larly with  heavy  cars,  it  is  exceedingly  liable  to  break  an  axle  or 
rend  a  tire.  Should  this  accident  occur  under  these  conditions, 
the  main  clutch  should  be  immediately  thrown  out,  and  the 
steering  wheels  held  strongly  in  the  direction  in  which  it  is  de- 
sired to  travel.  On  no  account  should  the  brakes  be  applied  ex- 
cept as  a  last  resort.  Even  then,  it  is  a  questionable  procedure, 
and  one  liable  to  disarrange  the  steering,  rather  than  check  the 
undesired  motion. 

Common  Causes  of  Failure  to  Operate. — In  addition  to  the 
causes  already  enumerated  for  the  failure  of  the  motor  to  start 
or  run  properly,  we  may  mention  several  other  conditions  which 
will  produce  the  same  result.  These  are:  (i)  an  imperfect  com- 
bustion, owing  to  a  bad  fuel  mixture ;  (2)  imperfect  compression, 
owing  to  leaks  in  the  cylinder  or  to  defective  valves ;  (3)  dirt  or 
water  in  the  carburetter. 

Troubles  with  the  Sparking  Apparatus. — In  case  the  driver 
suspects  that  the  failure  of  the  motor  to  operate  is  due  to  some 
trouble  with  the  sparking  apparatus,  producing  imperfect  com- 
bustion, he  may  readily  verify  his  suspicions  by  advancing  the 
spark.  As  stated  by  a  well-known  authority  on  motor  vehicle 
operation :  "If  the  motor  does  not  miss  with  the  spark  advanced, 
you  may  rest  assured  that  the  trembler  needs  adjustment ;  if,  on 
the  other  hand,  varying  the  position  of  the  spark  lever  does  not 
alter  the  condition  of  things,  then  there  must  be  either  a  wire 
loose,  or  the  gasoline  mixture  must  be  at  fault.  To  adjust  the 
mixture  move  the  gas  lever  back  and  forth.  If  the  engine  sticks, 
it  means,  you  may  rest  assured,  that  there  is  a  wire  loose  or  a 


GASOLINE  VEHICLE   OPERATION.  635 

short-circuit  somewhere.  Go  over  the  wiring  carefully  and  see 
that  the  same  is  properly  fastened  to  the  sparking  plug  and  to 
the  battery  terminals.  If  the  trouble  still  continues,  there  must 
be  a  short-circuit."  This  short-circuiting  is  probably  due  to 
breaking  down  of  the  insulation  in  the  sparking  plug  or  to  a  col- 
lection of  carbonaceous  material  between  the  sparking  points. 

Troubles  Due  to  Breakage  or  Wear. — In  case  the  motor 
suddenly  ceases  to  run,  there  are  three  common  causes  to  which 
the  trouble  may  be  attributed:  (i)  Breakage  of  the  exhaust 
valve ;  (2)  sticking  or  breaking  of  the  inlet  valve ;  (3)  short-cir- 
cuiting of  the  sparking  plug.  The  trouble  due  to  either  of  the 
first  two  of  these  causes  may  be  readily  discovered  by  turning 
the  starting  handle,  and  finding  no  resistance  or  compression, 
such  as  should  normally  be  encountered. 

In  case  the  exhaust  valve  should  be  found  broken,  it  is  neces- 
sary to  insert  a  new  valve  in  the  seat,  being  careful  to  see  that 
all  reciprocating  parts  are  properly  adjusted  and  of  the  right 
length  to  interact.  The  sticking  of  the  inlet  valve  may  be  caused 
by  excessive  heat  or  a  catching  of  the  spring,  although  either  of 
these  troubles  is  rare.  If  the  valve  or  its  spindle  be  broken,  the 
only  thing  to  be  done  is  to  replace  it. 

Causes  of  Imperfect  Combustion. — There  are  several  causes 
to  which  imperfect  combustion  may  be  attributed :  (i)  the  valve 
may  be  pitted  or  clogged ;  (2)  a  leak  may  have  occurred  around 
the  thread  of  the  sparking  plug;  (3)  a  compression  tap  may  be 
loose  or  leaking ;  (4)  the  piston  rings  may  be  clogged  or  stuffed ; 
(5)  the  piston  rings  may  work  around,  so  that  the  spaces  between 
their  ends  get  in  line;  (6)  the  gasket  of  the  sparking  plug  may 
be  broken;  (7)  the  inlet  valve  spring  may  be  too  weak,  which 
fault  accounts  for  an  occasional  popping  noise  in  the  carburetter. 

The  first  difficulty  may  be  overcome  by  grinding  the  valve, 
which,  however,  is  an  operation  just  as  well  left  to  skilled  ma- 
chinists. 

Any  leak  that  may  be  discovered  around  the  thread  of  the 
sparking  plug  may  be  readily  remedied  by  screwing  the  plug 
home.  Troubles  with  the  piston  rings  may  be  remedied  by  re- 
moving the  piston  from  the  cylinder  occasionally  and  thoroughly 
cleaning  it.  Where  the  rings  are  found  to  work  around  the  cylin- 


636  SELF-PROPELLED    VEHICLES. 

der,  the  piston  must  be  taken  out  and  the  rings  placed  in  their 
proper  relative  positions.  Any  trouble  with  the  spring  of  the 
inlet  valve  may  be  remedied  by  substituting  a  new  spring. 

The  matter  of  dirt  or  water  in  the  carburetter  is  a  serious  one 
in  motor  vehicle  management.  Water  in  the  carburetter  neces- 
sarily results  from  vaporizing  of  the  gasoline.  Since  this  liquid 
always  contains  certain  portions  of  water,  it  is  necessary  to  peri- 
odically drain  the  carburetter  and  remove  it,  as  well  as  any  other 
waste  materials  that  may  happen  to  be  present. 

Non-Freezing  Water  Jacket  Solutions. — According  to  popu- 
lar opinion,  largely  borne  out  in  practice,  it  is  difficult  to  operate 
a  gasoline  vehicle  in  winter  time,  owing  to  the  freezing  of  the 
jacket  water,  or  to  excessive  cooling  of  the  cylinder.  In  this 
belief  several  manufacturers  of  vehicles  propelled  by  air-cooled 
motors  advertise  their  respective  products  as  "The  only  service- 
able winter  vehicle."  While  it  is  undoubtedly  difficult  to  obtain 
good  results  from  a  gasoline  vehicle  in  attempting  to  start  in 
cold  weather,  it  is  possible  to  largely  neutralize  the  difficulties 
due  to  the  freezing  of  the  jacket  water  by  mixing  certain  chemi- 
cals in  the  water.  As  already  stated,  various  authorities  recom- 
mend a  solution  of  equal  parts,  by  weight,  of  water  and  glycer- 
ine ;  others,  a  saturated  solution  of  chemically  pure  calcium 
chloride  mixed  with  equal  parts  of  water,  by  measure.  As  al- 
ready stated  on  page  369,  any  motorist  attempting  to  use  the 
latter  solution  should  carefully  avoid  substituting  the  so-called 
chloride  of  lime  for  the  desired  calcium  chloride.  Another  solu- 
tion, which  is  recommended  by  other  authorities,  should  consist 
of  a  mixture  of  water  and  glycerine,  the  latter  being  about  30 
per  cent,  of  the  former  by  weight,  and  adding  to  this  mixture  two 
parts,  by  weight,  of  carbonate  of  soda.  This  liquid  should  be 
entirely  drawn  off  and  removed  once  a  month. 

Another  trouble  encountered  in  running  a  gasoline  vehicle  in 
cold  weather  is  the  difficulty  of  properly  vaporizing  the  fuel.  This 
condition  may  be  largely  neutralized  by  properly  heating  the  car- 
buretter in  the  manner  provided,  as  we  have  seen  in  a  number 
of  typical  instances.  At  all  times  heating  materially  assists  the 
process  of  vaporizing. 


CHAPTER  FOURTY-FOUR 

GASOLINE    MOTOR    CYCLES. 

Gasoline  Motor  Cycles. — While  there  appears  to  be  no  very 
definite  limit  to  the  size  and  power  of  heavy  and  high-powered 
motor  cars,  beyond  the  point  at  which  greater  increase  involves 
greater  liability  to  wear  and  disablement  of  metal  structures  and 
tires,  it  seems  that  a  serviceable  vehicle  may  not  be  produced 
below  a  certain  size  and  weight.  There  are  various  reasons  for 
this,  among  which  may  be  mentioned  the  difficulty  of  producing 
a  structure  at  once  sufficiently  light  and  sufficiently  strong  to  fill 
the  requirements  in  a  small  vehicle.  Again,  it  is  very  difficult,  if 
not  quite  impossible,  to  include  on  such  a  machine,  particularly 
on  a  bicycle,  the  desirable  and  necessary  regulating  and  con- 
trolling devices  required  with  any  type  of  motor.  The  latter  re- 
striction holds  since  the  rider  of  a  motor  bicycle  is  too  fully 
occupied  in  maintaining  his  balance,  and  in  guiding  his  machine 
through  the  intricacies  of  traveled  highways  and  over  the  diffi- 
culties of  rough  roads,  to  have  much  attention  to  spare  for  the 
manipulation  of  apparatus  requiring  the  exercise  of  either 
strength  or  judgment.  Nevertheless,  there  seems  to  be  a  strong 
sentiment  in  the  public  mind  that  a  light  motor  vehicle  is  the 
ideal  for  ordinary  service ;  the  demand  for  such  is  constant,  and 
several  firms  in  America  are  doing  a  large  business  in  manufac- 
turing motor  cycles,  especially  bicycles,  exclusively.  The  many 
grave  practical  difficulties  in  the  way  of  success  seem  to  example 
the  high  perfection,  to  which  the  science  and  art  of  motor  con- 
struction has  been  brought. 

It  may  be  interesting  to  note  that  the  motor  cycle  is  the  pioneer 
in  nearly  every  department  of  automobile  construction,  since  the 
earliest  modern  examples  of  both  steam  and  gasoline  motor  were 
equipped  to  propel  such  vehicles.  Thus,  as  we  have  seen,  Daim- 
ler's first  high-speed  gasoline  motor  was  arranged  to  propel  a 
bicycle,  while  Serpollet  made  the  preliminary  trials  of  his  "flash" 
generator  and  single-acting  steam  engine  on  a  tricycle  of  reason- 
able lightness.  One  or  two  ingenious  inventors  have  produced 

637 


638  SELF-PROPELLED    VEHICLES. 

electrically  propelled  bicycles,  but,  as  must  be  obvious  on  reflec- 
tion, such  a  machine  can  be  no  more  than  a  curiosity ;  the  weight 
of  the  batteries  quickly  limiting  its  range  of  travel,  and  the  low 
efficiency  of  a  small  sized  motor  still  further  limiting  its  service- 
ability. At  the  present  day  the  gasoline  cycle  is  the  only  one  that 
is  attempted  or  demanded. 

Requirements  of  a  Motor  Cycle. — According  to  experience 
in  the  matter,  a  motor  cycle  must  be  propelled  by  an  air-cooled 
motor,  preferably  of  rather  low  speed  and  of  somewhat  higher 
power  rating  than,  is  actually  required  for  the  load  to  be  carried. 
The  reasons  for  both  conditions  are  readily  discoverable,  since, 
having  dispensed  with  the  water-cooling  and  circulating  system 
for  sake  of  lightness  and  compactness,  it  is  desirable  to  avoid 
such  causes  of  overheating  as  unusually  high  speeds,  and  such 
low  power  as  would  cause  the  engine  to  labor  under  ordinary 
loads.  Some  bicycles  have  been  constructed  for  racing  purposes, 
with  an  advertised  speed  of  60  miles  per  hour  and  over,  several 
of  them  having  been  equipped  with  a  motor  guaranteed  to  de- 
velop six  horse-power,  a  rating  far  in  excess  of  demands  for 
carrying  one  person  over  an  even  roadway.  At  best,  such  ma- 
chines are  bulky  and  heavy,  out  of  all  proportion  to  convenience 
of  handling  or  for  ordinary  service.  Even  with  some  machines 
designed  for  ordinary  road  service,  and  having  an  extreme  speed 
limit  of  more  than  25  or  30  miles  per  hour,  the  motor  used  is 
guaranteed  to  develop  2,  and  even  3  horse-power  at  between 
1,200  and  1,500  revolutions  per  minute — speeds  seldom  attempted. 

Regulating  Attachments  on  Bicycles. — The  motor  bicycles 
manufactured  in  America  use  jump  spark  ignition,  almost  without 
exception.  Few  of  them  also  have  any  regulating  devices  other 
than  levers  for  varying  the  time  of  the  spark  and  the  opening. of 
the  valves — thus  modifying  the  speed — and  a  cut-out  switch 
located  conveniently  on  the  handle  bars,  for  the  purpose  of  stop- 
ping the  motor.  Adjusting  the  mixture  of  varying  the  time  of 
the  spark  are  the  typical  means  provided  for  changing  the  speed. 
It  is  obviously  impracticable  to  include  such  change-speed  gears 
as  are  used  on  heavy  vehicles  and  even  on  some  tricycles,  since 
the  rider  would  be  quite  unable  to  operate  such  with  safety, 
certainty,  and  convenience. 


GASOLINE  MOTOR  CYCLES.  639 

One  excellent  make  of  American  motor  bicycle  has  dispensed 
with  the  spark  advancing  apparatus,  and  varies  the  speed  solely 
by  interrupting  the  sparking  circuit.  A  published  description 
of  this  machine  sets  forth  the  system,  as  follows:  "This  cycle 
will  run  at  a  speed  of  from  5  to  25  miles  an  hour  at  the  rider's 
discretion,  and  is  under  perfect  control  all  the  time.  The  in- 
stant the  switch  plug  is  pressed  down  the  power  is  off,  and  at 
the  same  instant  the  compression  in  the  engine  acts  as  a  brake  on 
the  rear  wheel,  which  with  the  application  of  the  brake  on  the 
front  wheel,  brings  the  machine  to  a  stop  as  quickly  as  is  possible, 
without  a  sudden  stop.  The  timing  of  the  spark  can  always  be 
maintained  by  the  adjustment  of  the  screw  without  removing 
any  parts  of  the  motor, 

"By  the  elimination  of  the  advance  spark  mechanism  this 
company  claims  that  the  machine  has  been  much  simplified.  They 
claim  they  have  demonstrated  that  a  stationary  spark  is  a. per- 
fect method,  and  the  speed  is  regulated  by  the  amount  of  gas  fed 
to  the  engine.  The  rider  controls  his  speed  without  removing  his 
hands  from  the  bars.  A  slight  pressure  of  the  thumb  on  the 
switch  plug  interrupts  the  electric  current  and  shuts  off  the 
power  instantly,  a  pressure  of  the  index  finger  on,  the  other  end 
of  the  switch  plug  again  completes  the  electric  circuit  and  throws 
on  the  power.  This  enables  him  to  increase  or  slacken  his  speed 
by  pressing  a  button." 

One  of  the  things  to  be  most  avoided  in  motor  bicycling 
is  skidding,  which  is  obviously  much  more  dangerous  than  with 
foot  propelled  machines.  A  well-known  English  authority  writes 
as  follows  on  this  point,  illustrating  the  usefulness  of  certain 
constructions : 

"It  is  generally  known  that  an  exhaust  valve  lifter  is  indis- 
pensable in  this  connection ;  but  a  very  delicate  carburetter  which 
does  not  fail  to  give  mild  explosions,  when  the  throttle  is  nearly 
closed,  and  which,  in  conjunction  with  mechanical  valves,  will 
keep  the  engine  running  Mead  slow,'  is  a  useful  safeguard  against 
skidding.  The  next  safeguard  is  a  flexible  drive.  Advantage  in 
this  direction  will  be  derived  from  having  the  flywheels  much 
larger  without  being  heavier.  The  jerks  will  be  diminished  and 
as  it  is  the  beginning  of  a  slip  that  must  be  avoided,  every  trifle 
counts.  Also,  if  these  larger  flywheels  were  to  rotate  in  the  op- 
posite direction  to  the  road  wheels,  then  gyrostatic  action  would 


64:0  SELF-PROPELLED    VEHICLES. 

assist  the  rider  in  keeping  vertical  instead  of  acting  in  the  opposite 
sense,  as  they  do  now."  Exactly  how  his  ''gyrostatic  action" 
could  be  obtained  our  authority  does  not  specify,  although  the 
principles  laid  down  seem  to  possess  some  element  of  truth. 

One  or  two  of  the  earlier  types  of  motor  bicycles,  driving  by- 
belt  direct  from  the  motor  shaft,  had  two  separate  pulleys — a 
large  and  a  small  one — attached  on  either  face  of  the  rear  wheel, 
thus  enabling  the  adjustment  of  speed  before  starting  the  vehicle, 
by  belting  in  either  one  or  the  other.  It  is  obvious,  however,  that, 
with  a  direct  belt  connection  and  a  single  reduction,  it  is  far  more 
convenient  to  regulate  the  speed  and  power  output  of  the  motor 
than  to  rely  upon  any  form  of  variable  gearing. 

Arrangement  of  the  Motor. — In  the  arrangement  of  the 
motor  on  a  bicycle  there  has  been  a  wide  diversity  of  design.  In 
some  makes  it  has  been  supported  on  the  back  stays,  between  the 
pedal  bearing  and  the  rear  wheel ;  in  one  make,  on  an  extension 
of  the  back  stays  to  rear  of  the  wheel;  in  several  makes  it  is 
supported  against,  or  forms  a  part  of  the  rear  or  saddle  tube 
member  of  the  "dimond"  frame.  The  favorite  position  with 
most  machines  at  the  present  time  is  on  the  forward  member  of 
the  frame,  in  front  of  the  pedal  bearing,  or  on  a  tube  arranged 
beneath,  and  suitably  trussed  to  hold  the  weight. 

The  Transmission. — The  method  of  driving  is  practically  al- 
ways by  belt  from  a  small  pulley  on  the  motor  shaft  to  one  of 
much  larger  diameter  on  the  hub  of  the  rear  wheel.  Most  bicycles 
also  have  chains  from  the  sprocket  on  the  pedal  bearing  to  an- 
other on  the  rear  wheel,  for  use  in  starting  or  in  case  of  disable- 
ment of  the  motor,  and  arranged  to  be  thrown  out  by  some  form 
of  ratchet  or  "coaster  brake,"  as  soon  as  the  wheel  is  turned  by 
the  motor,  thus  having  the  pedals  stationary  in  travel.  The  belts 
used  for  this  purpose  are  generally  twisted  rawhide,  and  the 
length  may  be  regulated,  either  by  adjustable  jockey  pulleys  or 
by  unhooking  the  two  ends  and  twisting  or  untwisting  the  strand 
to  suit  requirements.  The  use  of  hide  belts  is  determined  mostly 
by  considerations  of  durability  and  safety,  since  the  best-made 
chains  are  liable  to  snap  at  high  speed,  with  the  result,  on  a 
motor  bicycle,  of  disabling  the  rear  wheel,  or  of  whipping  up 


GASOLINE  MOTOR   CYCLES.  041 

violently  against  the  rider.  A  hide  belt  could  break  under  sim- 
ilar conditions  without  dangerous  consequences. 

Apart  from  the  considerations  just  specified,  the  belt  drive  is 
the  only  really  effective  method  of  economical  power  trans- 
mission. 

One  or  two  bicycles,  notably  the  Wolfmuller  and  Holder  ma- 
chines, have  had  two  or  four-cylinder  motor  direct  connected 
to  cranks  on  the  rear  axle.  Another  had  the  motor  hung  upon 
the  axle,  which  it  turned  through  an  internal  reduction  gear. 
Both  these  arrangements,  however,  involve  the  disadvantage  of 
losing  power  for  the  doubtful  end  of  increasing  speed,  and  have 
been  entirely  abandoned  by  modern  constructors. 


The  Auxiliary  Apparatus. — The  other  essential  parts  of  a 
motor  bicycle  are  the  carburetter  and  gasoline  tank,  the  battery, 
the  induction  coil  and  the  oiling  apparatus,  all  of  which,  from  the 
necessary  limitations  of  construction,  are  made  as  compact  as 
possible.  Several  bicycles  have  used  a  combination  of  gasoline 
tank  and  carburetter,  as  in  the  De  Dion  cycles,  the  whole  appar- 
atus being  included  between  the  four  tubes  of  the  diamond  frame 
above  the  pedal  bearing;  the  motor  being  fed  through  a  special 
mixing  valve.  The  favorite  apparatus  at  the  present  time  seems 
to  be  some  form  of  float-feed  sprayer  operating  to  draw  the 
supply  from  the  tank  located  conveniently  under  the  upper 
member  of  the  frame  or  over  the  rear  wheel.  One  or  two  bicy- 
cles at  least  use  simple  mixing  valves  of  the  general  type  already 
described  under  the  head  of  the  James  valve.  With  either  spray- 
ers or  mixing  valves  the  prime  desideratum  is  the  possibility  of 
throttling  or  of  regulating,  as  the  only  available  means  of  con- 
trolling the  speed  of  the  vehicle.  The  battery  consists  gener- 
ally of  two  or  three  dry  cells  in  a  suitable  box,  no  case  being  at 
hand  in  which  a  magneto  or  dynamo  was  seriously  attempted  as 
a  source  of  current.  The  ignition  circuit  in  most  machines  corre- 
sponds in  general  features  with  the  De  Dion  and  other  secondary 
spark  arrangements  already  described,  including  an  induction 
coil  of  standard  pattern,  and  generally  also,  a  condenser. 

The  lubricating  apparatus  is,  of  course,  important,  especially 
for  supplying  the  cylinder  and  engine  bearings,  and  in  the  ma- 
jority of  modern  bicycles  consists  of  an  adjustable  oil  cup  with 


642  SHIP-PROPELLED    VEHICLES. 

sight-feed  attachment.    The  feed  is  thus  rendered  automatic,  ex- 
cept for  periodical  regulations. 

The  Framework  and  Wheels. — The  framework  and  wheels 
of  motor  bicycles  are,  of  course,  stronger  and  heavier  than  in 
foot-propelled  machines.  The  tubes  are  made  with  thicker  walls, 
and  the  joints  are  more  securely  reinforced.  In  several  makes 
the  end  of  security  is  further  assured  by  struts  and  trusses,  par- 
ticularly at  the  fork  on  the  steering  post  and  at  the  place  where 
the  motor  is  hung.  The  diamond  frame  is  practically  universal, 
although  several  of  the  earlier  types — notably  the  Wolfmuller 
and  Lawson — used  the  drop  frame.  In  the  Holden  bicycle  the 
frame  consisted  of  a  single  tube,  joined  to  the  steering  post  in 
front  and  bent  downward  to  carry  the  drive  wheel  in  a  fork  at 
the  rear.  The  back  stays  were  extended  forward  to  hold  the 
motor  and  other  apparatus,  and  were  further  supported  from  the 
main  tube  by  a  dropping  tubular  member  at  front  and  rear. 
The  pedals  in  this  machine  were  geared  to  the  forward  wheel,  as 
in  old-fashioned  velocipedes. 

Jar=Absorbing  Devices. — One  great  disadvantage  in  motor 
cycle  construction  is  the  practical  difficulty  of  arranging  any 
form  of  spring  or  cushion  device  to  take  the  vibration  of  the 
motor.  Several  makes  of  machines  include  some  spring  arrange- 
ment in  the  saddlepost  for  easing  the  rider,  but  the  framework 
must  be  built  to  endure  the  vibration  of  travel  on  rough  roads, 
and  at  all  speeds.  The  wear  and  strain,  as  miay  thus  be  seen,  is 
immense.  The  only  way  to  neutralize  this  element,  moreover, 
is  to  provide  the  motor  with  extra  heavy  flywheels,  in  order  to 
equalize  the  movement  as  far  as  possible.  One  excellent  type 
of  high-powered,  high-speed  machine,  which  has  won  excep- 
tional records  in  a  number  of  tests  and  races,  has  an  extra  large 
flywheel  (between  18  and  21  inches,  according  to  power),  and  the 
claims  are  that  this  "keeps  the  motor  steady  and  does  away  with 
the  heavy  vibration  in  some  high-powered  machines."  For  ma- 
chines intended  for  ordinary  speeds  such  great  additional  weight 
is  hardly  necessary. 

Brakes  for  Motor  Cycles. — The  question  of  brakes  is  an  im- 
portant one  with  motor  bicycles  and  cannot  be  setlled  off-hand 


GASOLINE  MOTOR  CYCLES.  643 

without  some  consideration  of  conditions.  The  principal  diffi- 
culty involved  in  using  a  shoe  brake  of  ordinary  bicycle  design 
on  the  forward  wheel  is  that  the  sudden  stop  would  result  in 
even  worse  consequences — owing  to  higher  speeds  and  greater 
weights — than  the  foot-propelled  machine.  There  are  also  a 
number  of  constructional  and  practical  difficulties  involved  in 
the  attempt  to  use  a  positive  brake  on  the  rear  wheel.  In  the 
majority  of  machines,  therefore,  the  front  wheel  brake  is  omitted, 
and  the  braking  of  the  rear  wheel  largely  relegated  to  the  com- 
pression of  the  motor,  after  the  interruption  of  the  sparking  cur- 
rent. Several  makes  of  bicycle,  however,  are  now  equipped  with 
a  type  of  friction  roller  brake  on  the  forward  wheel,  consisting 
of  two  small  rubber  rollers,  whose  axes  are  set  at  a  wide  angle, 
so  that  their  peripheries  brush  against  either  side  of  the  tire, 
when  pressure  is  exerted  on  the  hand  lever.  The  advantage  of 
such  a  device  is  that,  while  the  motion  of  the  machine  is  effectu- 
ally checked,  the  stop  is  not  so  sudden  as  to  result  in  disastrous 
consequences  to  rider  or  motor. 

The  construction  of  a  motor  bicycle  precludes  the  possibility 
of  closely  observing  the  operation  of  the  parts  in  the  course  of 
ordinary  travel.  It  is  desirable,  therefore,  as  has  been  indicated 
by  several  authorities,  to  have  a  stand  of  such  shape  that  the 
machine  may  be  hung  free  of  the  ground  and  set  in  motion.,  in 
order  to  afford  opportunity  to  watch  the  motion  and  note  any 
unevenness  that  may  occur.  The  principal  troubles  to  be  diag- 
nosed in  this  manner  are  those  relating  to  the  action  of  the  spark- 
ing circuit,  although  it  is  frequently  necessary  to  employ  such 
means  of  discovering  troubles  with  the  moving  parts. 

Motor  Tricycles  and  Quadricycles. — Although  the  bicycle  is 
the  most  familiar  form  of  motor  cycle,  the  tricycle  and  quadri- 
cycle  are  occasionally  seen,  and  hence  demand  some  brief  de- 
scription. The  primary  distinction  between  a  cycle  and  any  other 
type  of  motor  vehicle  seems  to  be  that  the  former  is  provided 
with  a  saddle  and  is  started — or  may  on  occasion  be  propelled — 
by  pedals.  A  tricycle,  then.,  is  a  vehicle  of  this  description  having 
two  rear  wheels  and  one  forward  wheel,  and  a  quadricycle,  one 
provided  with  four  wheels,  two  front  and  two  rear.  The  most 
important  distinction  between  the  two  types  is  that  the  quadri- 
cycle has  a  forward  axle  with  two  wheels — generally  also  carry- 


SELF-PROPELLED    VEHICLES. 

ing  a  seat  for  an  extra  passenger  instead  of  the  single  forward 
wheel  of  the  tricycle ;  both  types  being  steered  by  handle  bars 
from  the  driver's  saddle.  In  fact,  very  many  quadricycles  are 
merely  "converted"  tricycles,  and  almost  any  tricycle  may  be 
changed  into  a  quadricycle  by  substituting  the  two-wheeled  fore- 
carriage  for  the  single  steer  wheel. 

Speed  Gear  Tricycles. — Owing  to  the  different  style  of 
frame,  enabling  such  cycles  to  stand  alone,  also  to  permit  of  the 
ready  and  certain  manipulation  of  positive  gearing,  it  is  pos- 
sible to  include  speed-changing  attachments,  generally  giving 
two  forward  speeds,  but  no  reverse.  A  differential  gear  is  also 
necessary  on  the  rear  axle.  Since  the  drive  axle  of  most  tricycles 
is  at  least  four  feet  in  length,  there  is  sufficient  room  for  hanging 
the  motor  and  all  other  necessary  apparatus — the  battery,  coil, 
and  gasoline  tank  between  the  rear  wheels.  Unless  the  change 
gear  is  arranged  to  be  thrown  in  or  out,  no  clutch  is  provided.  In 
several  motor  tricycles  the  speed  is  controlled  solely  by  throttling 
the  motor  or  varying  the  spark,  thus  involving  that  the  motor 
is  always  in  gear,  to  act  either  as  a  driving  power  or  brake.  Shoe 
brakes  have  also  been  used  on  the  tires  of  tricycles,  but  this  con- 
struction is  not  so  common  as  a  band  on  the  differential  drum. 

With  the  motor  constantly  in  gear  the  only  method  of  over- 
coming its  resistance,  when  it  is  necessary  to  drive  by  the  pedals 
is  to  remove  the  sparking  plug  or  loosen  the  spur  pinion  on  the 
main  shaft.  The  former  operation  is,  or  course,  the  easier,  and, 
on  the  whole,  the  more  effective;  the  effect  being  to  neutralize 
the  compression  resistance  by  allowing  air  to  circulate  freely  in 
the  combustion  chamber.  Many  cycles  are  provided  with  a  spe- 
cial exhaust  valve  lift  to  keep  the  valve  open  when  the  motor 
is  not  needed,  as  when  descending  hills,  or  when  it  is  necessary 
to  use  the  pedals.  The  first  object  is  also  attained  by  the  use  of 
the  compression  tap  on  the  head  of  the  cylinder,  either  device 
operating  to  prevent  the  drawihg-in  of  fuel  charge  and  to  do 
away  with  the  resisting  effect  of  cylinder  compression.  Should 
it  be  desirable  to  utilize  the  braking  effect  of  the  piston,  the 
cylinder  may  be  closed  and  allowed  to  operate,  minus  the  spark- 
ing circuit. 


INDEX. 


Ackerman  stud  steering  axle,  36-41.  Boiler,  steam,  baffle  plate,  556. 

Air  cooling  for  gas  engines,  201-205.  feed    pumps,    586,    587,    588-591,    594, 

Air-cooling  device,  Crest,  203,  204.  595. 

Franklin,  204.  flues,  551,  552,  553-556,  557. 

Knox,  202,  203.  attachments  of,  579-585. 

Regas,  205.  excessive  pressure  in,  583. 

Simms,   201,   202.  feeders  for,  586-595. 

Air  feed  pumps,  594,  595.  heating  surface  of,  551-553. 

Alarms,  low  water,  584.  sectional  construction  in,  558. 

Ampere,  the,  428.  steel  or  copper  flue,  553-556. 

Ampere-second,   429.  water-tube,  558-567. 

Angle  iron  underframes,  68,  377,  378.  water  tube,  advantages  of,  558. 

Angles  of  steering,  46,  47,  52,  53.  Boyle's  Law  of  Gases,  526,  179-184. 

Atkinson's  gas   engine,   191,   211.          •  Brakes  for  road  wheels,  146-152. 

"Auto"   carburetter,  255-257.  care  of,  152. 

Automobiles,   types  of,   1-6.  constricting  band,  148,  149,  152 

Automatic  valves,  591-593.  constricting  effort  in,  146. 

Axles,      steering,      Ackerman's      stud,  diameter  of  drum  of,  147. 

36-41.  drum  and  band,   146. 

Daimler,   40.  expanding  band,  151,  152. 

Duryea,   38.  formula  for  acting  distance,  150. 

Haynes-Apperson,    39.  formula  for  required  pull,  151. 

Loomis,   41.  formula  for  resistance  to,  148,  149. 

Panhard,  48.  principle  of  torque  in,   147. 

Riker,  42.  requirements  in,  146. 

shoe,  146. 
varieties  of,   151. 

Baffle  plates,   556.  Burner  for  volatile  fuels,  596-608. 

Bailey   pneumatic   tire,   115.  fuel  regulators  for,  599-601. 

Balance    gears,    24-34    (see    differential  gasoline,   597,   598. 

gears).  "torch"  igniter,  605,  606. 
Balancing  of  gasoline  motors,  305-311. 
Ball  bearings,  153,  154. 

limitations   of,   155,    156.  Cadillac   carburetter,   340,   342. 

Band  brakes,   operation  of,   147.  control   apparatus,   418-422. 

B,  &  P.  pneumatic  tire,  117.  gasoline  carriage,  418-422. 

Bearings,    rotative,    balls    and   rollers,  gasoline  engine,  339-342. 

153,   154,   155.  transmission,    419-422. 

conditions  of  using,  155-157.  valve  cear,  340,  341. 

overcoming  friction  by,   153-155.  Calorific  value  of  volatile  fuels,  228-231. 

superiority  to  plain  bearings,  153.  Carburetters,    338,    406-423,    166,    170,    172, 

theory  of,  153,  154.  242-259. 

uses  of,  153.  "Auto,"  255-257. 

Belt    transmission,    Daimler,    347,    348,  Cadillac,  340,  342. 

300,  345,  346.  Centaure,  321. 

Benz  motor,  9.  Daimler,    243-245,    247,    249,    250,    251, 

ignition   circuit,   282-285.  257. 

muffler,  Ills.,  210.  Daimler-May  bach,    246,    249,    250. 

Blow  off  cock  of  steam  boilers,  585.  De  Dion,  172,  251,  252,  259. 


646 


INDEX. 


Carburetters  (continued}. 

Duryea,  250-252. 

Hayn^s-Apperson,   391-393. 

Huzelstein,  253-255. 

James,  254,  255. 

Krebs,  322. 

Longuemare,  246,  247. 

Maybach,  244-246. 

Olds,  343,  344. 

Peugeot,  248. 

troubles  with,  257,  258. 
Church's  steam  carriage,  16-18. 
Circulating  pumps,  200. 
Circulation,  jacket  water,  200. 
Clutch,  Columbia,  403. 

Packard,   382,   384. 

Peerless,  386,  387. 

Pope-Toledo,  396. 
Coil  vaporizers,  606-608. 
Compensating  gears,   24-34   (see  differ- 
ential gears). 

Columbia   gasoline   carriage,   398-403. 
Control  apparatus,   Cadillac,   418-422. 

Columbia,  401,  402. 

Daimler,   358-360. 

Decauville,  366,  367. 

Duryea,  403,  404,  409. 

Locomobile,  380,  381. 

Olds,  412,  414-416. 

Packard,  384-386. 

Panhard,   351,   352,   353-356. 

Stevens-Duryea,   417,   418. 

Winton,  368,   369,  370-373. 
Controller,  electric  circuit,  491-495. 
Coolers,   air,   for  gas   engines,   201-205. 
Coulomb,  The,  429. 
Counter  electromotive  force,  428. 
Creeping  of  pneumatic  tires,   127-129. 
Crest  air-cooling  device,  203,  204. 
Crossley's  gas  engine,  191,  192,  217,  218. 
Cugnot's  automobile,  7,  8,  21. 
Cut  off,  steam  engine,  533,  534,  547,  548, 
549. 

varying  point,  549. 

Cycle  of  gas  engines,   167,   168,   169,   170, 
208,   214-216. 

of  steam  engines,  532,  533,  534,  535, 

536,  539. 
Cycles,    gasoline,   636-644. 


Daimler,  Gottlieb,  8,  243. 
Daimler,  axle,  steering,  40. 

belt  transmission,  300,  345,  346,  347, 
348. 


Daimler  (continued). 

carburetter,   243,    244,    246,    249,    250, 
251,  257. 

carriages,   244,  249,   345-350,   357-359. 

control  system,  358-360. 

differential   gear,    34. 

gasoline   engine,    173,    176,    180,    182, 
297,   298,  299,  300,   305,   306. 

gear,  transmission,  345-347,  358-360. 

governor,  299,   301-303. 

hot  tube  ignition,  173,  263-265. 

piston  air  valve,  300. 

reversing  gear,  358-360. 

V-shaped  engine,  299,  300,  305,  306. 
Daimler-Maybach  carburetter,  246,  249, 

250. 

Daniell  cell,  428. 
Decauville  gasoline  carriage,   361-367. 

gasoline  engine,  361-365.     > 

transmission,  365,  366. 
De  Dion-Bouton,  9. 

carburetter,  172,  251,  252,  259. 

carriage,     67,    89,    90,     91,    171,    252, 
422-424. 

gasoline    motor,    171,    186,    308,    311. 
312,  323,  324. 

jointed  axle,  90. 

jump-spark  circuit,  278-282. 

reversing  gear,  424. 

speed-changing  device,  422,  423. 

steering  gear,  50,   89. 

underframe,   67. 
Diesel  gas  engine,  173,  211,  260,  261,  263. 

ignition  method,  260,  263. 
Differential  gears,  24-34. 

bevel,  27,  28. 

Brown-Lipp,  29,   30. 

Daimler,  34. 

for  tricycles,   25. 

Riker's  hub,  32. 

spur,   28-31. 

Thorny  croft's,  33. 

universal  joint,  31. 
Drum  brake,  diameter  of,  147. 
Dunlop  pneumatic  tire,  120,   128,  141. 
Duryea,    Charles   E.,   73,   79,   98,   99,   194, 
197. 

axle,    steering,   38. 

brake,  expanding  band,  152. 

carburetter,  250-252. 

carriage,  2,   38,   70-72,   74,   403-410. 

control  system,  403,  404,  409. 

gasoline   engine,    194,   223,   327,   337- 


INDEX. 


647 


Duryea  (continued). 

ignition  apparatus,  274,  275,  339. 

pneumatic   tire   experiments,    135- 
139. 

reversing  gear,  408-410. 

single  lever  control,  409. 

speed-changing  device,  405-408. 

steering  pivots,  38,  76. 

three-wheeler,  70,  73,  74,  75,  76. 

Dynamo-electrical    generator,    265,    273, 

281,  436-458,  514,  520,  521,  522. 

armature  of,   439,   440,   442,   443,   445, 
446,  447. 

amature  core,  442. 

armature,    polarization   of,   445-447. 

brushes  of,  439,  440,  445. 

commutator  of,  440,  443,  444. 

field  magnets  of,  440. 

operation  of,  439,  440,  445-448. 

pole  pieces  of,  440. 

varieties  of,  441. 
Driving  axle,  Thornycroft,  33. 


Edison  storage  battery,  518,  519. 
Electrical  activity,  426,  430. 

back  pressure,  428. 

circuit,  Ohm's  law  of,  429,  430. 

condenser,  426. 

current,  426,  439. 

dynamos  and  motors,  438. 

ignition,  173,  174,  265-296. 

induction,   436,   437. 

motor    and    dynamo    comparison 
of,   448,   449. 

armature  of,  449,  450. 
attachments  of,  451. 
speed  and  torque  of,  451,  452. 
varying  speed  of,   483-495. 

potential,  426. 

pressure,   429. 

quantity,   429. 

resistance,  427. 

units,  426,  427. 

Electricity,  as  a  force,  426. 
Electricity   meters,   431-435. 
Electric  carriages,  merits  of,  4-6. 
Electric  cells,   open-circuit,   266. 

primary,    266,   425. 

secondary,   266,  267,   425,   496-522. 
Electric  motors  for  carriages,  459-477. 

compound,   470-473. 

construction   of,    459-461. 

development  of,  468,  469. 

efficiency  of,  462,  463. 


Electric  motors  (continued). 

geared,   466,  467. 

general  electric,  461,  462,  463. 

Lundell,   465,   466. 

operation  of,  447,  448,  453. 

power  of,  453-458. 

requirements  in,  461,  462. 

series,  463,  464. 

shunt  and  compound,   470-472. 

speed  and  power  of,   464-466. 

troubles   with,   478-482. 
Electromotive  force  (E.  M.  F.),  426,  429, 

430,  442,  445,  448. 

Expansion    of    steam,    526-529,    532,    534, 
535,  536,  547-549,  550. 


Feeders  for  steam  boilers,  586-595. 
Feed  regulators  for  volatile  fuels,  574, 

599-601. 

Field  tube  boilers,  183,  184. 
Flash  "boilers,"  9,  568-578. 

Haythorn  joints  for,  577. 

Rowe  tubes  for,  577,  578. 

Serpollet,   166,   568-571,   577. 

varieties  of,   572-578. 
Flues,  boiler,  551-556. 

copper,   superiority  of,   553-556. 

heating  surface  increased  by,  551, 
552. 

number  of,  552,  557. 
Fore-carriages,  21,  58,  59. 
Fouillarion   pulley   transmision,   348. 
Franklin  air-cooling  device,   204. 
Fuel  feed  pump,  588,  590. 

regulators,   574,   599-601. 
Fuels,  hydrocarbon,   liquid  or  volatile, 
7,  166,  168,  169,  596,  597. 

burners  for,  597,  598,  601-605. 

calorific  value  of,  228-231. 

feed  regulators,  574,  599-601. 

for  gas  engines,  166,  168,  169,  172, 
178-183,  188,  189,  192,  193,  194,  206- 
209,  228-231,  242-259. 

vaporizing    and    burning    of,    297, 


G.  &  J.  pneumatic  tire,  119,  139,  140. 
Gas  engine,  advantages  of,  165,  166. 

Atkinson,  191,  211,  214,  215,  216,  217, 
220. 

conditions  of  operation,  177-179. 

cooling   cylinders   of,   190-205. 

Crossley,  191,  192,  217,  218,  220. 


648 


INDEX. 


Qas  engine  (continued). 

cycle  of,  167,  168,  169,  170,  208,  214- 

216. 

cycle  of,  Otto,  167,  168,  169,  208,  216. 
Diesel,  173,  211,  260,  261,  263. 
efficiency  of,  221-231. 
estimating    horse-power    of,    232- 

24L 

fuel  mixtures,  206,  207. 
governors  for,  175,  176,  302,  303,  304, 

312-319,   313,   314,   316,   317,   318,   369- 

372. 
Hornsby-Akroyd,  173,  191,   196,  207, 

261-263. 

heat  and  power  losses  in,  209-220. 
ignition  of  charge  in,   173,   206-220, 

260-296. 

method  of-  starting,  168. 
operative  principles,  165-241. 
Otto,  173,  263. 
parts  of,  171-177,  180. 
piston,  167,  170,  174,  175,   176,  177. 
theory  of,  166-168. 
volatile  fuels  for,  166,  168,  169,  170, 

174,    178-183,    188,    189,    192,    193,    194, 

206-209,   228-231,  242-259. 
Gases,  Boyle's  law  of,  526,  179-184. 
Gay  Lussac's  law  of,  529. 
Joule's  law  of,  532. 
pressure   and  volume  of,   526,   179- 

184. 
temperature   and   volume   of,    529, 

530,  531,  180,  186-188. 
Gasoline  burners,  597-608. 
Gasoline  carriage,  breakage  and  wear 

in,  635. 

"Buffalo,"   226. 
Cadillac,   418-422. 
Columbia,    398-403. 
Daimler,  345-348,  357,   358-360. 
Decauville,  361-367. 
De  Dion,  67,  89,  90,  91,  133,  422-424. 
directions  for  starting,  632. 
Duryea,  2,   38,  50,  53,  70-72,  74,   194, 

275,  336-338,  403-410. 
Locomobile,  376-381. 
Haynes-Apperson,  39,  99,  274,  390- 

394,  510-513. 
Hertel,  36. 
Knox,  73,  75. 
merits  of,  3,  4. 
Mors,  83,  315,  352. 
Olds,   411-416. 
Packard,  314,  315.     316,  324-326,  381- 


Gasoline  carriage  (continued). 

Panhard,  35,  48,  87,  305,  306,  316,  320, 
321,   322,  323,  324,  350-357. 

Peerless,  114,  386-390. 

Peugeot,   352. 

Pope-Toledo,  395-398. 

Pretot,  58. 

Smith  &  Mabley,  355. 

Stevens-Duryea,   416-418. 

Winton,   313,   314,   315,   367-376. 

cycles,  636-644. 
Gasoline  engine,  balancing  of,  305-311. 

Cadillac,  339-342. 

construction,  318. 

Daimler,  173,  182,  297-301. 

Decauville,  361-365. 

De  Dion,  171,  312,  323,  324. 

development,  320-322. 

dimensions  in,  309,  310. 

Duryea,  223,  336-338. 

failure  of  to  operate,  G30,  631. 

Ford,  335-337. 

Gobron-Brillie,  310,  311. 

Haynes-Apperson,  307,  332-334. 

imperfect  combustion  in,  630,  631. 

Knox,  202,  203. 

Locomobile,  328-330. 

Olds,  342-344. 

opposed  cylinder,  332-337. 

Packard,  324-326. 

Pope-Toledo,  330-332. 

Simms,  201,  202. 

St.  Louis,  326. 

starting  point,  630. 

Stevens-Duryea,  333,  334,  335. 

three-cylinder,  307,  308. 

valves,  319. 

Winton,  369-375. 
Gauge  glass,  check  valve  for,  581. 

indications  of,  579: 

troubles  with,   580-582. 
Gauge,  steam,  582,  583. 

Duplex  steam  and  air,  583. 

varieties  of,  582. 

Gay  Lussac's  Law  of  Gases,  529. 
Gear,  balance  (see  differential  gears) 
24-34. 

compensating      (see      differentia 

gears),  24-34. 

Generation  of  steam,  524. 
Generator,    dynamo-electrical,   265,    273 
281,  436-458,  514,  520,  521,  522. 

Holtzer-Cabot    magneto.    267,    268 
333. 

magneto,  267-272. 


INDEX. 


649 


Generator  (continued). 

magneto,  construction  of,  268-270. 

magneto,  operation  of,  270,  271. 

Simms-Bosch   magneto,   270-272. 
robron-Brillie  gasoline  motor,  310,  311. 
Joodyear  pneumatic  tire,  122,  141,  142. 
Governor,  Daimler,  176,  302,  303,  312,  313. 

for  gas  engines,   176,   302,   303,   312- 
318,  369-372,  391-393. 

Haynes-Apperson,  391-393. 

Packard,  314,  315-360. 

Peugeot,  304,  312,  313. 

Pope-Toledo,   316,   317. 

Riker-Locomobile,    317,   318. 

Winton    pneumatic,    313,    314,    315, 

372-374. 

Graphite  as  a  lubricant,  161. 
Grappler  pneumatic  tire,  121. 
Gurney's  steam  carriage,  10-13. 
Hancock's  steam  carriage,  13-16. 
Haynes-Apperson  axle,  39. 

carburetter,  391-393. 

carriage,  39,  99,  390-394. 

gasoline  engine,  307,  332-334. 

governor,  333,  391,  392. 

speed-changing  device,  393,  394. 


Haythorn    joints    for    flash    "boilers," 

577. 
Heating  surface  of  steam  boilers,  551- 

553. 

Hertel  carriage,  36. 
Hornsby-Akroyd    gas    engine,    173,    191, 

196,   207,   261-263. 
method  of  ignition,  261. 
Horse-power,  in  steam  engines,  536-539. 
Hot  tube  ignition,  Daimler,  173. 
Hurtu  electric  carriage,  55. 
Huzelstein  carburetter,  253-255. 
Hydrocarbon,  fuels,  7,  166,  168,  169,  596, 

597. 


Ignition,  173,  174,  260-296. 
Benz  circuit,  282-285. 
circuit,  troubles  with,  631,  632,  634, 

635. 

Dayton  electric,  365,  373,  374,  382. 
De  Dion,  278-282. 
Diesel  method,  260,  261. 
electrical,  266-296,  314,   315,   316,  334, 

338. 

Hornsby-Akroyd  method,  261,  262. 
hot  head,  173,  261,  262. 


Ignition  (continued). 

hot  tube,  173,  262,  263-265. 

Otto  method,  262,  263. 

results  of,  206-220. 
Indicator,  steam  engine,  528,  529. 
Injector,  boiler  feeding,  586. 

Jacket  water  circulation,   200. 
James  carburetter,  254,  255. 

steam  carriage,  17. 
Jointed  axle,  De  Dion,  90. 
Joule's  Law  of  Gases,  532. 
Jump-spark  circuits,  276-296. 


Knox  air-cooling  device,  202,  203. 
carriage,  73,  75. 
gasoline  engine,  202,  203. 

Lap  and  lead,  of  steam  valves,  541-543, 

545,  546,  547,  549. 
Leclanche  cell,  429. 
Lemp  steering  check,  59. 
Leverage,  balance  of,  37. 
Lifu  compound  steam  engine,  625-627. 

water  tube  boiler,  565,  566. 

wheel  for  truck,  110. 
Link   motion,    Stephenson,    543-547,    549, 

612,  625. 
Locomobile  gasoline  carriage,   376-381. 

gasoline  engine,  327,  328-330. 

governor,  317,  318. 

lubricating  system,  330. 

running  gear,  377,  378. 

steam  carriage,  64,  157,  551-553,  609, 
610,  611-613. 

transmision,  379,  380. 
Locomotives,    construction    of   wheels, 

44,  45. 

Longuemare  carburetter,  246,  247. 
Loomis  steering  axle,  44. 
Low  water  alarms,  584. 
Lubricants,  159-161. 

feed  cups  for,  160. 

for  gas  engine  cylinders,  159,  160. 

graphite,  its  use  as,  161. 

qualities  essential  in,  162. 

superiority  of  mineral,  160. 

tests  and  qualities  of,  161,  162. 
Lubricating  device,  Cadillac,  341. 

Locomobile,  330. 

Winton,  371,  372. 

oil  pump,  163. 
Lussac's  Law  of  Gases,  529. 


650 


INDEX. 


McKay  steam  carriage,  66. 

underframe,   66. 
Magnetic  field,  445. 

distortion  of,  446,  447. 

induction,  438,  445. 

units,   454-458. 

Magnetism,  residual,  442,  445. 
Magneto-electrical  generators,  267-272. 

construction  of,  268-270. 

Holtzer-Cabot,  267,  268. 

operation  of,  270. 

Simms-Bosch,   270-272. 
Magnets,  538. 

production  of,  437. 

properties  of,  437,  438. 
Meters,  electricity,  431-435. 
Michelin  pneumatic  tire,  118,  139,  140. 
Miner's  inch,  542. 
Mors'   carriage,   83. 

ignition   apparatus,   339.    . 

throttling  device,   315. 
Motor,  electric,  operation  of,  453. 
power   of,    453-458. 

wneels,  23. 
Muffler,  Benz,  210. 
Multiple  circuit,  543,  566. 
Munger  pneumatic  tire,  123,  142. 

Ohm's  law,  544,  545. 
Oil  feed  cups,  160. 

pumps,   lubricating,   163. 
Oils,  organic,  useless  for  automobiles, 

160. 
Olds'  carburetter,  343,  344. 

control  system,  412,  414-416. 

gasoline  carriage,   411-416. 
engine,  342-344. 

transmission,   414-416. 

valve  gear,  343. 

Otto,  Dr.  N.  A.,  his  gas  engine  cycle, 
167,   168,   169,  208,   216. 

gas  engine,  173,  263. 

method  of  ignition,  263,  264. 

Packard  brakes,  382,  384. 

clutch,  382,  384. 

control   system,   384-386. 

gasoline  carriage,  381-386. 
engine,  324-326. 

governor,  314,  315,  316. 

transmission,  384-386. 
Panhard-Levassor,  9. 

axle,  steering,  48. 

carriage,  35,  48,  87,  305,  306,  316,  320, 
321,  322,  323,  324,  350-357. 


Panhard-Lcvai-gor  (continued). 

.change-speed  gear,  353-357. 

control    system,    351,    352,    353,    354, 
356. 

engines,  306,  316,  320-322. 

light  car,  35. 

reversing  gear,  355,  357. 

spark  regulator,  288. 

steering  connections,  48. 
Parallel  circuit,  428,  483. 
Peerless  carriage,  114,  386-390. 

clutch,  386,  387. 

transmission,  389,  390. 
Peugeot,  9,  304,  313. 

carburetter,  248. 

carriage,  248,  350,  352. 

governor,  304,  313. 
Piston  air  valve,  299,  300-302. 

gas   engine,    167,    170,    174,    175,    176, 
177. 

steam  engine,  527,  531,  533,  539,  540, 

541,  543,  548,  614,   615,   621. 
Pneumatic  tires,  effects  of,  84-86. 

experiments,    Duryea,    135-139. 

Tillinghast,  124,  126. 

plugs,   spark,   293-296. 
Pope-Toledo  clutch,  3%. 

engine,   330-332. 

gasoline  carriage,  395-398. 

governor,  316,  317. 

spark  regulator,  287. 

transmission,  £97,  £93. 
Poppet  valves  for  gas  engines,  167,  17:], 

174. 
Pressure,  of  steam,  526-528,  530-532,   534, 

535,  536,  539,  550. 
Prctot  carriage,  58. 
Primary  spark,  272-278. 
Pump  air  feed,  594,  595. 

fuel  feed,  588-590. 
Pumps,  boiler  feed,  586-595. 

circulating,  200. 

lubricating  oil,  1G3. 

Reading  steam  carriage,  65. 

underframe,  65. 
Regas  air-cooling  device,  205. 
Regulators,  fuel  feed,  599-601. 

thermostat,  574. 

Resiliency  of  pneumatic  tires,  134-139. 
Reversing  gear,  Daimler,  358-360. 

De  Dion-Bouton,  424. 

Duryea,  408. 

Haynes-Apperson,   464,   466. 

Panhard-Levassor,   392,   394. 

Winton,  372,  373. 


INDEX. 


651 


Riker  axle,  steering,  42. 

carriage,  32,  42,  69. 

differential  gear,  32. 

underframe,  69. 

Rods,  distance  or  radius,  82,  83,  87. 
Roller  bearings,  153,  154. 

conditions  of  using,  156,  157. 

constructional  points  on,  157,  158. 
Rowe  tube  for  flash  boilers,  577,  578. 


Safety  valves,  584,  585. 
Scavenging  cylinder,  210-213. 

stroke,  168. 

Searchmont  spark  regulator,  288. 
Separators,  steam,  556,  557,  524. 
Series  circuit,  428,  483. 
Serpollet,  Leon,  9,  166. 

engine  and  carriage,   614-616. 

flash  generator,  9,  166,  568-571,  577. 

water  feed  system,  588-590,  591. 
Shunt  dynamos,  441,  442. 
Side  slipping,  633,  634. 
Simms  air-cooling  device,  201,  202. 

gas  engine,  201. 

Simms-Bosch  sparking  circuit,  272. 
Slide  valve,   steam  engine,  540,   541-543, 
544,    546,    547,    549,    551,    612,    614,    615,    616, 
619,  620,   622,   627. 

Smith  &  Mabley  gasoline  carriage,  355. 
Spark  plugs,  293-296. 

primary,  272-278. 

regulators,   287,   288. 

timing  of  the,  285-288. 

gap,  the  outside,  289-292. 
Sparking  circuits,   265,   272,   279,   282,   283, 
286,  291. 

circuit  breakers,  280,  281,  284,  285. 
Speed-changing   devices,   345-424. 

belt  and  pulley,  347-349. 

Daimler,  347,   349,  367-369. 

De  Dion-Bouton,   422-424. 

Duryea,  404-408. 

Fouillarion,   348. 

Haynes-Apperson,   392,   393. 

Panhard-Levassor,    353-357. 

Winton,  372-374. 
Springs,  80-93. 

attachments   for.    88,   89. 

construction  of,   89-91. 

dimensions  of,  83,  84,  8G,  87. 

formulae  for,  91,  92, 

general  theory  of,  80,  81. 

suspension  of,  82,  83. 
Stanley  underframe,  64. 
Starting  a  gas  engine,  method  of,  168. 
Steam  and  air  gauge,  583. 

boilers,  advantages  of  water  tube, 
558,   559. 

attachments   of,   579-585. 

blow-off  cock,  585. 

circulation  in  water  tube,  558,  559. 

excessive  pressure  in,  584. 

feeders  for,  586-595. 

fire  flue  of,  551-557. 

"flash  boiler,"  568-578. 


Steam  (continued). 

heating  surface  of,  551-553. 
sectional  construction  in,  558. 
steel  or  copper  flue,  553-555. 
Thornycroft,  564. 
water  glass  of,   579-582: 
water  tube,  558-567. 
carriages,  merits  of,  2,  3. 

Church's,   16-18. 

Cotta,   56-58. 

Cugnot's,  7,  8,  21. 

Gurney's,    10-13. 

Hancock's,  13-16. 

James',   17. 

"Locomobile,"    64,    609-613. 

McKay,  66. 

Reading,  65. 

Stearns,   78,  92,  619-622. 

Serpollet,    568-571,    589-591,    614- 
616. 

Trevithick's,  9,  10. 
engine,   compound,   617-629. 
cut  off,  533,   534,   547,   548,   549. 

varying  point  of,  549,  617,  619. 
cycle  of,  532-535. 

estimating  horse  power,  536-539. 
indicator,  528,  529. 
reading  of  cards,  529,  532-535,  536. 
mean  effective  pressure,  539. 
operation  of,  540-550. 
operative  cycle  of,  532,  533,  534,  535, 

536,  539. 
piston,  527,  531,  533,  539,  540,  541,  543, 

548,  614,  615,  621. 

slide  valve,  540,  541-543,  544,  546,  547, 

549,  609,  612,  614. 
theory  of,   523-539. 

compared  to  other  gases,  523,  524. 
expansion   of,   526-529,   532,   534,   535, 

536,   547-549,   550. 
forms  of,  525,  526. 
gauge,  582. 
generation  of,  524. 
indicator    cards,    527,    528,    529,    532- 

535. 
pressure     of,     526-529,     530-532,     534, 

535,  536,  539,  550. 
pressure  and  temperature  of,  529- 

532,  535,  539. 

pressure  and  volume  of,  526-529. 
separators,   524,  556,  557. 
temperature    of,    524,    525,    526,    529, 

530,  535. 
valve,    lap    and    lead    of,    541-543, 

545,  546,  547,   549. 

Stearns  steam  carriage,  78,  92,  619-622. 
Steering,  angles  of,  46,  47,  52,  53. 
check,  59. 
gear,   Bolee,  53. 

Clarkson-Capel,    52. 

Cotta,  57. 

De  Dion,   50,  89. 

Duryea  three-wheeler,  38,  75, 

76. 

Gobron-Brillie,    51. 
Hurtu,  55. 
Knox,   75. 
Panhard,   48. 
rear  wheel,  58. 
Thornycroft,  49. 

Stephenson    link    motion,     543-547,     549, 
G12,  625. 


652 


INDEX 


Stevens-Duryea  control  apparatus,  417, 
418. 

gasoline  carriage,  41b-418. 

engine,  333,  334,  335. 
St.  Louis  gasoline  engine,  519,  520L 
Storage  batteries,  266,  267,  425,  496-522. 

Edison,  518,  519. 

electrolyte,  498,  505,  506,  511. 

"formation"  of,  500,  501. 

Gould,  500,   501,  506,   508,   510,   512. 

invention  of,  498,  499,  502. 

period  of  charging,  509,  514,  515. 

Plante,  499-508. 

principles  of,  498,  499. 

requirements  in,  499. 

varieties  of,  499-505,  518,  519. 


Temperature  of  steam,  524,  525,  526,  529, 

530,  535. 
Thorny  croft,   John   I.,   104. 

compound  engine,  618,  622-625. 

differential  gear,  33. 

driving  axle,  33. 

jointed  countershaft,  93. 

road  wagon  and  engine,  622-625. 

spring  road  wheels,  103,  104. 

steam  boiler,  564,  565. 

steering  gear,  49. 

wagon  underframe,  77. 
Three-wheeler,  Duryea,  70,  73,  74,  75,  76. 
Tillinghast,  P.  W.,  124,  129. 

latest  improved  tire,  125. 

pneumatic  tire,  124-126. 

single-tube,  124-126. 

timing  device,  automatic,  291. 
Tires,    pneumatic,    advantages   of,   112- 

attachments  for  double  tube,  139, 

140. 

Bailey,  115. 
B.  &  P.,  117. 

care  and  repair  of,  119-132. 
construction   of,    119-122. 
creeping  of,   127-129. 
Dunlop,  120,  128,  141. 
effects  of,  84-86. 
G.  &  J.,  119,  139,  140. 
Goodyear,  122,  141,  142. 
grappler,  121. 
Michelin,  118,  139,  140. 
Munger,  123,  142. 
on  bicycles,  85,  86. 
opinions   on,    113,    114,    116,    120,    121. 

124,  125,  135-139. 
proportions  of  ,132-134. 
puncture,   122-124. 
resiliency  of,  134-139. 
single  tube,   124-127. 
Tillinghast,   124-126. 
use  and  effect  of,  112-145. 
Tires,  solid  rubber,  attaching,  107,  111. 
comparison  with  pneumatics,  108, 

109. 

durability  of,  109,  110. 
merits  of,  106-108. 
opinions  on,  105,  107,  108,  109,  110. 
reducing  vibration,  105. 
structure  of,  110,  111. 
varieties  of,  107,  108,  109. 
Torch,  burner  igniting,  604,  605,  606. 


Transmission,  Cadillac,  419-422. 

Fouillarion,  348. 

"Locomobile,"  379,  380. 

Olds,  414-416. 

Packard,  384-386. 

Peerless,  389,  390. 

Pope-Toledo,  397,  398. 
Trevithick's  steam  carriage,  9,  10. 
Try-cocks,  579,  581. 

Underframes,  62-79. 

angle  iron,  68,  377,  378. 

De  Dion,  67. 

DuryQa,  70. 

flexibility  in,  64,  65,  66,  68,  69,  70,  73, 

78,   79. 
Knox,   72. 
McKay,  66. 
Reading,  65. 
Riker,  69. 

requirements  in,  62. 
Stanley,  64. 
three-wheeled,  73-79. 
tubular,  63. 

Valve,  automatic,  591,  593. 

by -pass,  586,  587,  588. 
Valves,  gasoline  motor,  319. 

lap  and  lead  of  steam,  541-543,  545, 
546,  547,  549. 

poppet,    for   gas   engines,   167,   173, 
174. 

"pop"  safety,  584,  585. 

safety,  584,  585. 

Vaporizers  for  fuel,  604,  605-608. 
Victor  steam  carriage,  551. 
Volatile  fuels,  7,  596,  597. 

vaporizing  and  burning  of,  596-608. 
Volt,  The,  429. 
Volt-ammeter,  431-434. 

indications,  435. 

indicator  band,  432. 

readings,  434,  435. 

scale,  433,  434. 

Water-cooling  devices,  200. 

jacket,  non-freezing  solutions  for, 

201,  636. 

Watt,  The,  430. 
Wheels,   construction  of,  94,  95. 

dimensions  of,  95,  96. 

dishing  in,  95,  96. 

double   interacting,    143-145. 

driving  on  all  four,  54-61. 

driving  on  front,  55-57. 

for  automobiles,  94-104. 

"Lifu"  steam  truck,  110. 

locomotive,  construction  of,  44,  45. 

motor,  23. 

on  using  large,  101-104. 

requirements  in,  94. 

steering  on  rear,  58,  59. 

Thornycroft  spring,  103,  104. 

tubular  steel,  102. 
Winton  carriage,  61,  367-376. 

gas  engine,  369-375. 

speed-changing  device,  373,  374. 

pneumatic  governor,   313,   314,   315, 
372,  373. 

racing  carriage,  375,  376. 

reversing  gear,  374. 


Mechanical  Notes  and  Data 


Mechanical  Notes  and  Data 


Mechanical  Notes  and  Data 


Mechanical  Notes  and  Data 


Rogers'  Progressive  Machinist,  $2. 


THE  PROGRESSIVE  MACHINIST  is  issued 
in  the  interest  of  those  (  r  )  who  as  yet 
are  uninformed  and  are  at  the  beginning 
of  a  career  devoted  to  mechanic  arts.  (2) 
Those  who  have  once  known  the  rules  and 
practices  of  the  machinist's  art  and  have  for- 
gotten much  of  that  which  they  once  painfully 
acquired.  (  3  )  For  all  whose  extensive  knowl- 
edge of  machines  and  machine  shop  practice 
will  be  rendered  more  available  by  a  scientific 
arrangement  and  indexing  of  what  is  gener- 
ally known. 

"It  is  narrated  of  the  good  sculptor, 
Michael  Augelo,  that  when  at  work  he 
wore  ovtr  his  forehead,  fastened  to  his 
cap,  a  lighted  candle,  in  order  that  no 
shadow  or  himself  might  fall  on  his  work. 
It  was  a  beautiful  custom  and  spoke  a 
more  eloquent  lesson  than  he  knew.  For 
the  shadows  that  fall  on  our  work  —  how 
often  they  fall  from  ourselves. 

"So,  it  has  been  the  aim  of  the  e.ditor 
and  compiler  of  the  pages  of  THK  PRO- 
GRESSIVE MACHINIST  to  keep  in  the 
shaded  background  allusions  to  those 
long  years  of  personal  experience  which 
have  gone  never  to  return,  but  upon 
whose  gathered  and  garnered  experience 
the  value  of  the  work  must  rest." 

The  domain  of  practical  mechanics  is 
now  so  vast  that  a  useful  book  must  be  largely 
suggestive  rather  than  minutely  explanatory, 
and  it  has  been  the  aim  of  the  author  to  pro- 
duce a  work  which  shall  be  not  only  instruc- 
tive but  stimulative  of  further  study. 

Mathematical  elements  are  woven  into 
the  work;  tables,  rules  and  examples  are 
"  worked  out  "  wherever  these  can  make  the 
reading  matter  plainer. 

The  contents  of  the  book  must,  perforce, 
be  its  own  justification;  to  be  thorough  and 
accurate  is  to  be  also  honest,  and  to  be  all 
three  is  worthy  of  the  highest  ambition;  and 
such  has  been  the  endeavor  of  the  author  in 
his  not  wholly  selfish  labors  in  producing 
the  volume. 

It  is  recommended  that  the  reader  shall 
consult  the  List  of  Contents  at  the  beginning 
of  the  work  for  reference  to  Subjects,  and 
refer  to  the  Index  at  the  back  of  the  work  for 
particular  findings.  The  latter  may  frequent- 
ly be  found  under  another  letter  where  failure 
has  been  made  in  one;  this  is  an  advantage 
gained  by  the  use  of  the  cross  index,  i.  e.,  a 
subject  is  entered  under  more  than  one 
heading. 

The  book  totals  — 


I  05  I 


Table  of  Contents. 


MATERIALS 

Preliminary  Definitions—  Materials—  Qualities  of  Matter—  Iron,  Steel,  etc.—  Vari- 
ous Metals,  Alloys,  etc.,  arranged  Alphabetically  —  Gravity  and  Tables—  Three 
I,aws  of  Motion  —  Historical  Note,  Strength  of  Materials  and  Table  —  Fatigue  of 
Metals  Table  of  Melting  Points  of  Solids—  Useful  Weights  and  Measures. 

SHOP  DRAWING 

Introduction  —Free-hand  Drawing—  Blackboard  Sketches  —  Drawing  Materials  —  In- 
struments —  Outfit  —  Drawing  Board  Tee-Squares-Triangles  or  Set-Squares  — 
Dividers  and  Compasses  —  Drawing  Scales  —  Two  foot  Rule  -  Protractor  —  Drawing 
Pens—  Penciling—  Inking—  lettering  Drawings—  Dimensioning—  Shading—  Section- 
I,ining—  Reading  Working  Drawings—  Problems  in  Geometrical  Drawing—  Points 
Relating  to  Drawing. 

GLARING 

Introductory—  Definitions—Cog  Wheels,  Spur  and  Bevel  Wheels—  Mitre  Wheel- 
Mortise  Wheel—  Rack  and  Pinion—  Worm  Gearing—  Helical  Wheel—  Internal  Gear 
\\heel-Designing  Gears  —  Proportions  of  Parts  —  Cast-Steel  Wheels  —  Speed  of 
Gear  Wheels. 

BENCH  AND  VISE 

Tempering  and  Hardening  Metals—  Physical  Properties—  Definition  of  Terms—  The 
Art  of  Tempering—  J.  Matthewson's  Method—  H.  Woodruff's  Method  —  American 
Machinist  Rules  —  Grades  of  Steel  —  Cementation  Process  —  Bessemer  and  Siemen- 
Martin  Process  —  Case-Hardening  —  Annealing  —  Hand  Tools—  Machine  Tools-^- 
Work  Benches  —  Vise-Hammer  —  Scribers  —  Steel  Square  —  Cold  Chisels  —  Files  — 
Calipers  —  Straight-Edge—  Center-Punch  —  Wrenches  —  Sledge  and  Anvil  —  Practical 
Use  of  the  Foregoing^—  Surfacing  —  Red  Marking  -Hand  Drilling  —  Broaching  — 
Screw  Cutting  by  Hand  —  Pipe  Cutting. 

TOOLS  AND  MACHINES 

Definition  of  Machine  and  Hand  Tools—  Portable  Tools  —  Action  of  Machines  —  Clas- 
sification of  Machine  Work  —  Turning  and  Boring  —  Planing  Operations  -Milling 
—  Drilling  —  Grinding  —  Punching  and  Shearing. 

THE 


Historical  —  Forms  and  Use  of  Foot  loathes  —  Hand  I,athes—  Chuck  or  Surfacing 
L,athe  —  Engine  loathe  —  Parts  of  the  loathe  —  Countershafts  -Cutting  Tools  Used  in 
the  loathe—  Tool  Room—  Tempering  of  loathe  Tools  Rule—  lyathe  Practice  -Meas- 
uring Instruments  —  Chucks  —  Mandrels—  Template  -  L,athe-Dogs  —  Centering  — 
Driving  Work  Between  Centers—  Turning  Work  Between  Centers  —  loathe  Speed- 
Chuck  and  Face-Plate  Work  —  Drilling  and  Boring  in  the  loathe—  Proportion  of 
Parts  of  a  lyathe  —  Summary. 

TABLES  AND  INDEX 

Weight  of  Plate  and  Sheet  Iron—  U.  S.  Standard  Gauge  for  Same—  Weight  of  Flat 
Iron—  Weight  of  Round  Iron  —  Weight  of  Square  Iron  —  Weight  of  Cast-Steel  Bars 
—  Comparison  of  U.  S.  Standard,  Birmingham  Wire,  and  Brown  &  Sharp's  Wire 
Gauges  —  Decimal  Equivalents  of  an  Inch  —  Diameters,  Circumferences  and  Areas 
of  Circles  -Index. 


SPECIMEN   ILLUSTRATION. 


Rogers   Advanced  Machinist,  $2. 


THE 

ADVANCED 
MACHINIST! 


ROGERS 


THEO.AUDEL 
&CO. 


1  I  'HE  preparation  and  issue  of  this  work  is 

aimed  to  point  the  way  of  advancement 
to  those  who  must  become  fitted  to  assume 
the  obligations,  as  well  as  to  receive  the  re- 
wards of  those  who,  in  the  order  of  things, 
must  give  place  to  the  coming-man. 

The  trade  of  the  machinist  is  peculiar  in 
that  it  is  a  preparation  for  so  many  positions 
outside  of  it.  It  takes  a  man  of  good  natural 
ability  and  of  considerable  education — not 
always  from  books — to  make  3,  first-class 
machinist,  and  more  of  the  same  to  make  a 
competent  foreman  or  a  superintendent;  so 
that  when  one  is  well  qualified  for  these  posi- 
tions he  is  also  well  prepared  for  many  other 
openings  with  which  the  machine  shop  appar- 
ently has  little  to  do ;  and  many  of  these  keep 
calling  him,  and  so  many  respond  to  the  call, 
so  that,  in  consequence  it  is  said  that  ' '  skill 
is  dying  out, ' '  that  ' '  skilled  workers  are  be- 
coming scarce,  that  soon,"  as  "things  are 
going,  we  will  be  left  behind,  in  the  world's 
markets,  by  the  lack  of  both  competent 
operatives  and  of  the  higher  skill  and  re- 
liability that  are  to  exercise  supervision  and 
direction." 

It  is  with  a  full  knowledge  of  these  facts 
that  in  "The  Plan  of  the  Work"  some  sub- 
ject matter  has  been  introduced  which  the 
author  is  confident  will  be  of  the  utmost 
value  in  the  shop  and  afterwards  as  well, 
when  the  student  "  makes  a  change." 

A  partial  outline  of  the  plan  and  scope 
of  the  work  is  printed  on  the  following  page. 
The  personal  character  of  the  book  appeals 
to  all  in  any  way  associated  in  the  machinery 
and  allied  trades. 

The  volume  contains 


334^304 


Illustrations 


70: 


Table  of  Contents. 


MATHEMATICS:  Notation,  Numeration— Addition,  Subtraction,  Multiplication  and 
Division  —  Reduction  —  Fractions  —  Cancellation— Decimals — Ratio — Proportion — 
Square  and  Cube  Roots — The  Metric  System. 

MENSURATION :  Measurements  of  Surfaces— Circles— Diameters  and  Areas  of  Circles 
— The  Ellipse — Solids,  all  with  Rules,  Examples  and  many  Illustrations. 

MEASURING  MACHINES:  End  Measuring  Rod— Inside  Micrometer  Gauges— 
Calipering  Machines — Corrective  Gauge  Standards— Limit  Gauge — Parallel  Meas- 
uring Gauge — Angle  Gauge — The  Vernier  and  its  Use. 

LATHES  AND  SCREW  CUTTING:  Screw  Machine— Boring  Mill— Cutting  Tools 
— Longitudinal  and  Cross  Feeds — Spline  Feed  Spindle — Sliding  Worm — Worm 
Wheel— Screw  Threads— Chasers— Guide  Screws— Fast  and  Movable  Headstocks— 
Carriers  or  Dogs — Change  Wheels — Pitch  of  Thread — Automatic  Slide — Rake  of 
Threads -Tool  Holders— Finishing  Off— Chalk  Marks -Graduated  Discs— Fixed 
Pointers — Calculating  Threads — American  and  English  Standard  Threads— Change 
Gears — Coarse  Pitch  Screws — Arrangement  of  Gear  Wheels — Spur  Gearing — Com- 
pounding Gears— Calculations— Index  Plates. 

BORING  MACHINES:  Horizontal  and  Vertical  loathe  Boring— Boring  Bar— Taper 
Holes— Key  Ways— Traveling  Heads— Tail  Stocks— Cutters— Internal  Bevel  Gear- 
ing—Belt Cone — External  Spur  Gearing— Cross  Rails— Power  Gears — Saddles- 
Tool  Bars— Friction  Discs— Feeds— Slip  Gears— Steady  Motion— Angle  Plates- 
Advantages — Smooth  Cutting— Skiveing— Roughing,  Side  and  Broad  Finishing 
Tools — Adjustable  Reamer—  Four-lapped  Roughing  Drill. 

BORING  OPERATIONS:  Planer,  Shaper  and  Slotting  Machines— Key- Way  Cutter 
— Devices  for  Feeding— Driving  Belts— Independent  Frictional  Devices — Narrow 
High  Speed  Driving  Belts— Rack  and  Pinion  Movement — Planing  Machines — 
Average  Cutting  Speed  for  Various  Metals — Cutting  Angles — Clearances  and  Tool 
Angles  for  Working  Various  Metals— Open-Side  Planer— Chucks— Planer  Centers 
— Varieties  and  Operations  of  Shaping  Machines— Fellows'  Gear  Shaper — Cutting 
External  Toothed  Gears— Internal  Gears— Gear  Cutter— Rotary  and  Reciprocatory 
Motions— Setting  Tools— Slotting  Machines. 

MILLING  MACHINES:  Modern  Milling  Machines— Universal  Milling  Machines- 
Speeds  for  Cutters — Tables  Milling  Speeds — Milling  Tools — Rose  Mills  or  Groove 
Cutters— Counter  Bore  Mills — Reamers — Face  Milling  Cutters — Angle  Cutters — 
T-slot  Cutters— End  Mills— Surface  Mills. 

DRILLING  MACHINES:  Drilling  and  Boring— Drilling  Machines— Vertical  Drill- 
Base  Plates— Pillow  Frames— Face  Plate— Spindle  or  Arbor— Pulleys,  Speed  Cones 
— Spur  Gears — Bevel  Wheels — Hand  Ratchets— Foot  Lever—  Feed  Motion — Hand 
Wheel— Balance  Weight  and  Chain— Radial  prills-Wall  Drills— Drills  Used  in 
Different  Machines — Care  and  Grinding  of  Drills — Drill  Chucks — Roughing  Drills 
—Reamers— Speed  Tables— Twist  Drills. 

GRINDING  OPERATIONS:  Grinding  Machines  in  Modern  Practice— Use  of  Rotat- 
ing Emery  or  Corundum  Wheel — To  Sharpen  a  Twist  Drill  and  Circular  Saw  on 
Emery  Wheel— Universal  and  Surface  Grinding  Machines— Straddle  Mill— Spiral 
Tooth  Cutters — Sharpening  Taps — Emery. 

PUNCHING  AND  SHEARING:  Punching  and  Shearing  Machines— Applying 
Power  to  Shearing  Machines — Punch,  Die,  Die  Block,  Die  Holder,  Socket,  Stripper, 
Edge  Gauge,  Pun  -hing  and  Shearing  Machines,  etc. 

BOLT  CUTTING  MACHINE:  Bolt  Thread  Cutter—  Movement  of  Carriage— Lubri- 
cation for  Dies— Stroke  for  Plunger— Oil  Tank— Bed  and  Slides— Headstock— Oil 
Pump  Clutch  Ring — Cutters — Steel  Caps— Cutting  Speeds  for  Dies  and  Taps. 

AUXILIARY  MACHINES:  Cutting-Off  Tool -Cutting-Off  Saw— Power  Hack  Saw- 
Set  Screws— Sliding  Thimbles— Varying  Pressure  on  Forward  Stroke— Magazine 
Coil  Principle — Speed  of  the  Blade — Flexible  Hack  Saws — Arbor  Press — Pressure 
Obtainable  —Gears  Used— Mandrels— Plunger  or  Ram  —Lever  Spindle— Beverage- 
Counterweights —  Shedder  —  Shaft  Straightening  —  Turrets,  How  Operated  and 
Aligned— Taper  Gibs— Changes  of  Feed— Turret  Drill— Screw  Cutting  Die  Heads 
— Tripping  of  Dies — Adjustable  Collapsing  Taps— Keyseating  Machine — Automatic 
and  Hand  Feed. 

UTILITIES  AND  ACCESSORIES:  Jigs— Shop  Pan— loathe  Pans— Trueing  Emery 
Wheels— Emery  Wheel  Dressing  Tools — Devices  for  Stamping  Metals— Screw 
Jacks— Sheave  Rope  Blocks— Automatic  Lock— Snatch  Blocks— Wall  Cranes— 
Water-pot  for  Grind  Stone -Buffing  Machine. 

SHOP  MANAGEMENT:  Organization,  Equipment  and  Management— Co-operation 
—Piece  Work  Plan— Differential  Plan— Premium  Plan— Equitable  Method— Plan- 
ning a  Shop— The  Foreman— Gang  Boss. 

USEFUL  WORKSHOP  RECIPES  :  Babbitt  Metal— Solders— To  Tin  a  Soldering 
Iron— Brazing  Cast  Iron— Cheap  Lubricant— Soda  Water  for  Drilling— Fusing 
Points  of  Tin-Lead  Alloys— Lime  to  Clean  Shop  Floors— Nickel  Plating  Solution- 
Marking  Solution— Brass  Bluing— Anti-Rust— Varnish  for  Copper— Removing 
Sand  and  Scale  from  Iron  Castings— Rust  Joint  Composition— Cement  for  Fasten- 
ing Paper  or  Leather  to  Iron— Extracting  Broken  Tools— Soldering  Fluids— Use  of 
Blue  Vitriol  in  Laying  Out  Work— Expansion  Metal— Oil  that  Will  Not  Gum. 

AIDS  TO  THE  INJURED:  Cuts  and  Wounds— Broken  Bones— To  Carry  an  Injured 
Person— Burns  and  Scalds— Heat  or  Sunstroke— Frost-bite— Foreign  Bodies  in  the 
Eye— Resuscitation  from  Electric  Shock— Colic— Bandages— Poultices,  and  Care 
of  Self. 

USEFUL  TABLES:  Surface  Speeds  for  Machining  Various  Metals— Speed  of  Saws— 
Average  Speed  for  Drills— Drills  for  U.  S.  Standard  Taps— Emery  Wheel  Speeds— 
U.  S.  Standard  Screw  Threads,  and  Standard  Sizes  of  Wrought  Iron  Welded  Pipe. 


Rogers'  Drawing  and  Design,  $3. 


T  T is  hardly  necessary  for  t  lie  publishers  to  mention  the  primary  importance 
*  of  a  Uiorough  knowlet/fe  of  drawing  and  design  except  to  say  that  this 
volume  is  arranged  for  a  comprehensive,  self -instruction  course  for  both  shop 
and  drawing  room. 

The  work  is  divided  into  three  parts,  embracing  twelve  divisions  or 
general  subjects. 

Part  One  relates  to  Linear  Drawing  and 
ends  with  page  202. 

Part  Two  relates  to  Machine  Design 
and  ends  with  page  408. 

Part    Three    is   devoted   to 
Mathematical  and  Useful  Ta- 
bles and  Data,  the  Use  of 
Dra  winglnstru  ments 
and  a  most 
ous    cross 
Index. 


The 

Table    of 
Contents,  print- 
ed on  the  opposite 
page,    will  convey  an 
idea  of  the  orderly  and  truly 
scientific  arrangement  of  the 
subjects  as  they  progress  from  ''Ab- 
breviations and  Conventional  Signs" 
to  the  " Logarithmetic  Table"  and  expla- 
nation of  its  use — the  latter  division  occupying 
no  less  than  27  pages. 

The  entire  work  contains  506  pages,  illustrated  by  over 
600  cuts  end  diagrams  very  many  of  them  full  page  draw- 
ings; the  book  is  printed  on  a  very  fine  grade  of  paper;  it 
measures  8y2  x  iol/2  inches  and  weighs  over  j  pounds;  the  binding  is  in  black 
cloth  with  gold  edges  and  titles;  the  volume  is  made  to  open  freely  and  is  in 
every  way  a  most  complete  up-to-date  book  both  in  contents  and  as  a  specimen 
of  high  standard  book  making. 


Table  of  Contents. 


PLAN  AND    SCOPE    OF  THE  WORK, 

ABBREVIATIONS  AND  CONVENTIONAL  SIGNS, 
USEFUL  TERMS  AND  DEFINITIONS, 

DRAWING  BOARD,  T-SQUARE  AND  TRIANGLES, 
LETTERING, 

SHADE  LINES, 

SECTION  LINING, 
GEOMETRICAL  DRAWING, 

ISOMETRIC  PROJECTION, 

CABINET   PROJECTION, 

ORTHOGRAPHIC  PROJECTION, 

WORKING  DRAWINGS,  DEVELOPMENT  OF  SURFACES, 

TINTS  AND  COLORS, 

TRACING  AND  BLUE  PRINTING, 

READING  OF  WORKING  DRAWINGS, 
MACHINE  DESIGN, 

PHYSICS  AND   MECHANICS, 

MATERIALS  USED  IN  MACHINE  CONSTRUCTION, 
SCREWS,  BOLTS  AND  NUTS, 

RIVETS  AND  RIVETED  JOINTS, 
POWER  TRANSMISSION, 

SHAFTS  AND  BEARINGS, 

METAL  WORKING  MACHINES,  BELTS  AND  PULLEYS, 

DIES  AND   PRESSES,  GEAR  WHEELS, 

DRILLING  AND  MILLING  MACHINES, 
THE  LATHE, 

ENGINES  AND  BOILERS, 

ELECTRICAL  MACHINES, 

DRAWING  INSTRUMENTS, 
LOGARITHMS,  TABLES  AND  INDEX. 


"One  peculiar  feature  of  the  draftsman's  opportunity  is  that  it 
takes  hold  of  all  the  mechanical  occupations,  and  of  one  almost 
as  much  as  of  the  other.  It  is  not  in  the  least  monopolized  by 
the  machinist,  and  it  is  not  the  necessity  of  his  shop  more  than 
of  the  others.  The  pattern  maker  certainly  has  quite  as  much 
to  do  with  working  drawings,  and  why  not  also  the  inolder, 
the  blacksmith,  the  boiler  maker,  the  carpenter,  the  copper- 
smith and  all  the  rest?  It  will  be  to  the  immense  advantage 
of  the  workers  in  any  of  these  lines,  and  to  the  young  man  a 
most  presumptive  means  of  advancement,  to  be  not  only  able 
to  read  drawings,  but  to  make  them."— American  Machinist. 


TLife 


